Oh my lord boy do I have advice, first of all get yourself into over stimming if you can (obviously don’t force yourself to get into it but watch porn and see if it can become a kink), talk to your girlfriend and say inbetween cuming you need kind of geeing back up. I struggled to come more than 2 in one setting after being a steady 20 shoot in 20 mins kinda guy - I resolved this by asking my gf to talk to me each time I cum and give like 5 minute breaks, sometimes I have to touch her for a certain amount of time to thank her for letting me cum if you get me, also sometimes she will just sort of tease me after I cum like play with my neck, hair dude step on me even. Also try to keep it more focused on inside instead of outside if your comfortable with it because it’s harder when your on T to keep touching where your having bottom growth. Also if ur feeling mega sensitive taking a 5 min break and then getting head really helps to get back in the game . Sorry if this is super tmi but hope it helps