Am I getting weaker?

Fear is a natural response to many situations in life. It can possibly save your life one day. Think about when we were exploring the "new world" and you saw a snake, you should feel fear because many snakes can kill. In today's world though we can feel fear for many things that we don't need to such as a business meeting or relationship issues. A movie quote says it well "Fear is not real. It is a product of thoughts you create. Danger is real but fear is a choice."
To feel fear is good and natural but to let fear control your actions and life is unhealthy. You mind is stronger than you think.

 

You haven't completely f**d yourself over. Luckily for all of us our brains are strong and it is doing what it is supposed to. It is us that need to change. Try to remember there isn't anything wrong with your brain or body, it doesn't need to be "fixed". The problem is with your actions which you are trying to fix. From what I understand that as you remove the porn and constant masturbation from your life the pleasing good feelings also go. In the beginning your brain returns all the chemicals associated with sex back to normal levels and ranges, this can cause a great boost in energy, confidence and sexual appeal. As this "high" beings to dwindle, due to your brain balancing out, you can experience a "crash" where you might feel sad, slow or depressed. Your brain is used to porn bringing happy chemicals and feelings, when you stop this you will have to find new things to do. Do things that you like or enjoy, such as reading, exercising, watching movies, hanging out with friends, watching comedy anything that will make you happy. This is the rebooting process, changing what you do that makes you happy. The "crash" varies from person to person, some guys don't experience it at all, some get really depressed, others find it difficult to get hard when they crash (i doubt you'll experience this cause of your age) and some it only lasts a very short time. It just depends on the person. The crash is only temporary and it is good because it means you are in good with the rebooting process.
You are doing really good man by making it to 18 days. There is nothing wrong with you, you are only improving yourself. This is your journey and always remember you are doing something excellent for your body mind and future. Remember that and do you best to enjoy the challenge.

 

This is not weakness my friend. I'm doing nofap for 2 years now with some relapses. And I must say these are just the ups and downs of nofap. You will feel emotions much harder with nofap. The best advice is to let them flow or just to meditate. Meditation is great to balance mind.