Overwhelmed by trying to save myself for my relationship

Hey guys, ill start with a backstory.

Im 21 year old male now, and over the last 4 years ive been in and out of relationships (3) and i was cheated on and humiliated in all 3 relationships. All of em were similar cases where i walked in on my GF at the time having sex with someone else, and 2 of em just looked at me and didnt stop.. So after the third time, i said i wouldnt date ever again, not for a long time at least, cos im the type of person where i give my everything to someone from the get go, which is my weakness. Then i met my current GF, who i have been dating for over a year now, and it's been amazing, but now im really struggling.

She's given me no reason at all to not trust her, cos i do, well i think i do, but then i get really anxious and panicky when they dont reply for ages, or leave late from work. I also have this constant need to know what shes doing and where she is, cos im just so scared im gonna get hurt again, but it's doing nothing but hurting her, cos she's not done anything wrong to deserve this. I've recently started trying to keep this in from her, in hopes i can control it, but im really overwhelming myself and i cant sleep, i cant be happy (unless im there with her, cos then i know whats going etc). 

The worst part about this, is that i keep getting negative things in my head, telling me that shes not replying cos shes cheating, when i know she isnt, but then i get really uneasy and anxious and have a mini panic attack.. It's not fair on her at all, and i dont wanna lose her cos shes the first person in this world to show me that there are good people out there. I dont know what to do and im losing my mind when i try to solve it.. I cant afford a counsellor, and i just dont know what to do. I haven't told her that this is driving me insane, cos i don't wanna scare her off, but she's gonna find out sooner or later and when she does, she'll probably leave me cos im not really worth the effort that'll cause in my opinion and i wouldn't blame her either..

Sorry for the long story, it was gonna be short but i kept finding myself saying more and more. 

I don't even know if i posted this in the right place, if not, then im sorry and you can delete it and ill repost in the correct place if i know where. 

Does your girlfriend know your history with the cheating in your other relationships? I think it will help if you let your gf read the message you just wrote. She will see how much you are struggling and it will help her understand what you are feeling. However, you have to learn to cope without a constant reminder of what she is doing at all times of the day. She has to be independent and you need her to be. You have to learn to trust someone again. If you can't afford counseling, go to the library and find a book about getting past infidelity or look online to find the best reviewed books related to this problem and buy one. Take steps to move past your fears before you sabotage your current relationship.

 

Sorry really late reply, been very busy at work!

She knows my history to a tee, and im just scared to show her this. I've told her everything i pretty much wrote in person, but it's just so difficult to fix something so broken as i am, and she feels im not even trying to fix myself, when i really am. 

I've read a couple of books, but they dont really help too much. Are there any you would recommend?

I have read Infidelity survival guide and surviving infidelity.

Again sorry for the late reply but thank you so much for replying. Means a lot to me