Hi, my name is Eliyahu. 
I struggle with this problem since I'm 15yrs old. I'm 27 now. It's very hard to control myself when I feel pain or hurt or neglected or don't understood. 
My goal is to become clean. I am probably addicted to it. It's very hard for me to not touch myself in these situations. 
My goal is from strength to strength. 
I was clean for 16 days before today. 
2 times I collapsed today. 

Welcome!!! The people here are supporting, caring, and understanding. All of us here have struggled, and continue to struggle. I myself am 37, and have been struggling since age 13.

Would you care to elaborate on "this problem"? Can you be a bit more specific? Look around at some of the stories posted on the forums, you will see regular people just like you, who struggle, just like you. The more you share your story, the more people can/will help you. 

What concrete steps have you taken so far in your battle? Are your devices filtered? What steps do you take to avoid pitfalls? 

hi, 16 days is great ! dont give up!  and keep on posting  

Welcome. It should be with hatzlocha. Keep posting and stay in touch.

Hello Yerushalmi. Thank you for your response. I struggle with masturbation. Also Porn addiction. I feel that after collapse on a clean period, the urge to do it is even stronger. It's like I have to get back for what I missed the past days. 

I haven't done a lot in prevention strategy. My phones are not filtered. 

First things first. Filter ALL of your devices!  I use the filter from GenTech, gentechsolution.com. It costs money, but I find it to be the best for my needs. Ask around on the forum, maybe others can tell you about other filters.
Secondly, you know the places (if any), where you go to get your porn fix. AVOID THOSE PLACES LIKE THE PLAGUE.
Thirdly, keep posting!!! The more you post, the more you are open with your struggles, the more the community can/will help you. I myself find it hard to post details of my private life in a public forum, even though everything is anonymous. I have opened up in a private chat, and told all. You can send a private message to anyone. Someone was kind enough to provide me with his email address and phone number, and I am in touch with this person! Find someone you can do this with as well. It is very awkward and uncomfortable to open up, but GYE is anonymous, and that makes it easier.  
Fourthly, Hashem is on your side, and is rooting for you. HE wants you to succeed! HE wants you to be clean! Every victory that you tally, no matter how tiny, is EXTREMELY precious in HIS eyes.  Ask HIM for help! Pour out your heart in tefilah. לב נשבר ונדכה, אלוקים לא תבזה 
Fifthly, and this is something that I only recently came to realize. You can't have it both ways. For years, I would try to keep clean, and at times was able to stay clean for 2-3 weeks. Yet, I would still look at inappropriate material online. This would of course almost guarantee me to eventually slip up. I now realize that as part of my goal to stay clean, all inappropriate material has to be avoided. Period. No room for discussions, no negotiations. It has to stop, entirely. If you firmly commit to going clean, you can do it. Included in that commitment is the avoidance of whatever triggers you. 
All the best!!!

Great post yerushalmi, especially the last point, you really can't have it both ways. And it is a tough pill to swallow...

It took me a long time to realize this. This was expressed in a different context by אליהו הנביא in last week's Haftorah

עד מתי אתם פוסחים על שתי הסעיפים? 

Welcome!  You say, " It's very hard to control myself when I feel pain or hurt or neglected or don't understood."  That is very important.  Do you have friends, family that you are close with.  Developing healthy relationships will go a long way to solving your problem.  You have identified your main triggers.  Now, you have to figure out how to deal with these emotions in a healthy way.  Friends and family can be a HUGE help.  We are here for you.  keep posting.