I’m a teen with a big problem—premature ejaculation

I know that I am one of many with the same question but I simply cannot find the right solution for it. I am 18 year old and have a pretty good relationship. We are 18 months together and 3 months ago we had our first intercourse. That was the first time for both of us. It wasn’t like I imagined it. I was stressed and ejaculated quickly. But for next few times I was pretty good and could last pretty well—I suprised myself. But then we started to have sex in my car. I am a teen so I don’t haven my own apartment and the car is the best solution right now. I thought everything would go fine because car is big and we have enough space. But immediately after I put my penis in her, I ejaculated. I was never so sensitive. The second time I usually last longer, but the last three times my second ejaculation happened as fast as the first. And now I cannot get an erection anymore. I love my girlfriend and I want her to enjoy sex with her. This is a really big problem for me—probably  psychological because I’ve tried kegels and everything. (I always use condoms and first few times we used lube.)