PIED & Climax Position Issues

First of all, welcome to the forum. You came to the right place for solving issues you have described here.
Firstly, you need to educate yourself as much as you can about the issues you are facing. There are good sources of information like this commnity, ybop website and so on, to understand what is addiction and how the symptoms work.

In short and simple, addiction (any, but especially porn addiction) is a chemical imbalance in a brain. Dopamine is a chemical which plays the most important role. During PMO (porn, masturbation and orgasm), huge amount of dopamine is released and brain gets less sensitive to it. Thats why a brain is searhing for more and more dopamine release to feel satisfied. During normal, healthy activities, there is no possibility of releasing such high amounts of dopamine.
PIED is the symptom of PA - dopamine release is necessary for erection. As brain is not so sensitive to dopamine anymore, and real/natural interactions can't release such high amounts of dopamine, erection does not happen.
The only cure is making the brain more sensitive to dopamine. Thats possible only by avoiding high dopamine activities (porn, masturbation and orgasm in the first place).
Of course that porn is the main culprit, but masturbation and orgasm are also high dopamine activities. Thats why getting better just by cutting out porn takes much longer (if its even possible) then cutting out all 3.

The only possibility, especially for more severe cases is abstaining from P, M and O for some time (few months in general) and then try to introduce interaction with real partners.

That is very simplified version, of course that conditioning to some thngs plays a role(you mentioned lying on your back, sheets and so on), conditioning to videos on your screen instead of a real person (smell, touch, body heat, taste...), but I would say that's secondary.
Anxiety plays a role, but its much more easy to cope with that after letting your body react in a natural way...like having morning erections, having erections just by kissing a girl or simmilar. Also, self confidence plays a role.

EDIT: Oh, I read it again and..you are not so new to this.
Ok, still, education is vital in my opinion.
You mention 2 month streaks.. I don't think it's enough to see some huge improvements in severe cases. You were changing your brain chemistry for 10 years, can't expect it will miraceously heal in 2 months. But it will after some time for sure!

Please, give yourself a chance. Try to cut out thinking about sex entirely for lets say 3 months. Try to concentrate on other aspects of your life ant try to make it better (your career, your physical shape, your knowledge...). Forget about PMO and girls completely. After 3 months reevaluate your state. How do you feel, what changes you see (like, career progress, your body apperance, morning and spontaneous erections, your self confidence). At that point you can estimate do you need more time to heal or are you ready to try to do something with a woman. If you need more time, take it. If you think youre ready, try to approach women and see where it goes. Just in either case don't test yourself with porn, masturbation or orgasm.

You will see that youll start to feel better, that your depression will gradually decrease and youll be able to improve your life.

 

Presence of morning erections even more confirms that physiologicaly everything works fine and you are not in such a bad state.
If depression is the consequence of PA or anxiety connected with that, after few months abstaining, it will certainly get better.
If the depression is induced by some other factor then it would be wise to search for some medical help.
In your case, it seems to me that the former is true.

Regarding short frenulum, I had that myself also. I was lucky and managed to stretch it so it works (its still a bit uncomfortable sometimes and its not perfect for condom use, but it works and I dont bother that much anymore).
I have a really close friend who had similar issue, went to the urologist and sorted it out quickly and painless (local anestetic and a small cut, he was out of the doctors office in 15 minutes, after that diazepam for a few days to avoid morning/night erection and he was cured). The latter option seems very easy and convenient - I would vote for that, you just have to go to see a doctor.

Regarding supplements, I dont know much. Personally, I take ZMA daily (magnesium and zinc) - it helps keeping testosterone in normal levels, muscles recover much faster and in my case it regulates bowel movements (thats why I take it in the first place), D vitamine (I take it for the skin - I have acne probably due to years of PMO) and Omega 3 acids (generally healthy but they should help recovering brain tissue as well and "brain plasticity", so it might help recovering healthy dopamine pathways).
Ive heard of many others, but most of them I didnt try and dont feel confident enough to suggest.

Oh, one more thing, I used ED drugs (sildenafil like viagra/kamagra) during my first interactions with women. Some say its not helpful if it isnt physically induced ED. In my case, I found it helpful because it slightly decreased my performance anxiety, which goes hand in hand with PIED, but dont rely on that.

 

Well, I have something in common with you too, I have a general transformation of anxiety, but thank God I learned to feel relaxed, listen to classical music, watch nature videos and do relaxation exercises, I recommend that you do the same.
I have in common with you also , that i never had sex, but in my case its because im christian , well I remember the last time i watch porn i masturmaded me , I get anxiety , so I talk to god , and I feel better .
I dont have girlfriend but im not watching for this , however if the oportunities appears i will take it , i recomend you to fight the good fight my brother.

 

At first I couldnt retract a foreskin due to the short frenulum, but I streched it daily few times to the point of pain but not over it. Thats why it became longer, but I never injured it or had any scars so it was easier. After a while, I could pull my foreskin and it worked ok.