Good post and good luck. I'm guessing you're still quite young, probably under 30. I had exactly the same problem when I became more sexually active. I worked out it was cos of all the wanking off to internet porn. My cock was basically only used to my left hand giving it a good rub out. Once it came near or entered any actual fanny then that mother nature thing kicked in less than ten strokes later it was over. Tried all the creams, muscle strengthening, delay condoms, early wank off, red bull, etc. but none of them worked effectively or consistently. Best was when I stayed off the porn for a few weeks then sex was always better. The more I stayed off the porn/wanking habit then gradually my timings improved. It's never going to be like porn, that's just fake, so I lowered my expectations. Too much foreplay is also not good for me.
Weirdly last year I fell ill and started taking anti-depressants. After a few weeks on them I could last for ages and somtimes not cum at all. A very strange feeling, knackering and frustrating at the same time. Not ideal in my experience. I'm still not a two pop person, that's something I'd love to crack. One step at a time though.
I hope some of this helps. Main thing is don't be hard on yourself, or embarrassed, or apologetic. Think of it like fitness training. There are no quick fixes and it will take time and some work to get results. And some of it is in the mind. Be realistic with your goals. Stop wanking.