I can't get erections properly and im 18, my dick cant stand up and stay hard and say erect, I can

You are very young, it seems you have PIED (porn induced erectile disfunction). It can also be caused by some diseases like dibetes. Let me ask you some questions:
1.Is everything OK with your health?
2.How much do you Porn->masturbate in average on a week?
3.How old were you when you started watching porn?

I also used to have PIED, it was similar to yours. I was able to get "hard " only by touching myself. And in most of the times it wasn't "hard enough". I improved a lot since I started doing nofap streaks, I'm now able to get full erections. Not just me, some men in this forum told me they were cured after long streaks. Go for it in hard mode

 

i starting around the same time and i am 29......gets hard for awhile and then drop......

 

That's a lot of fapping.
And it is probably the reason of your problem. I also used to do it a lot, I remember some days it was like 8 times, and I ended with PIED. Porn addiction is one of the causes of erectile dyfunction in our modern society.

You can try Nofap in hard mode it is not easy but quiting the addiction definitely worth it. Not only for your sexual health it also has a lot of bennefits for your life. If you are new to all of this you can read the guides:
https://nofap.com/porn-addiction/
https://nofap.com/rebooting/
If you have trouble or questions make a post here there is a great supportive comunity.

 

You much time you needed till you cured your pied?

 

Damn, you sound like you've got a Death Grip and PIED. Only way to fix this is to stop POM altogether for at least 1-2 months, ideally longer.

 

My progress was slowed down because I relapsed a lot at the begining. I was several months, more than a year, in those cycles of relpses but despite all of that, I also were improving my erections through that time. Last time I was able to perform really well in the intercourse. I wouldn't recomend that way, because relapsing dirrupts the improvements down there. It is much better hard mode for a few months, I'm doing it right now.