Getting him to last longer?

Hello friends, ive been around this bend a few times and i feel like a bitch asking bc hes the sweetest, funniest, most caring guy ive ever been with, but with a freaky side and isnt afraid to put me in my place need be (no worries, our relationship is super healthy! Been around the abuse bend once already with someone else). Hes a really good partner and support when i need him to be as well,, its just that sex can be... disappointing from time to time. Its inconsistent if im going to walk away with an orgasm(its hard for me to get off and i dont blame him for that) or satisfied. I know that's a petty reason (literally the only thing I'd consider "wrong" or something i don't like), and i feel awful even thinking "he'd be perfect if rhe sex was better" but let me tell you what weve tried so that maybe you guys can help us.

So what we have tried is

- the mandelay desensitizer cream. (we bought it at HEB once and he said it didnt really do anything)- the internet wasnt much help on. If that was a good choice of deseneitizer to use anyway.

-start-stop method. It has helped prolong our activities.

-longer foreplay. Similar to above bc it puts off the actual act of fucking me.

-using condoms. Meh to no improvement. There is no difference.

-he says that he adds numbers in his head to keep his mind off of the pleasure, it helps but he says it sort of kills the moment for him (and sometimes i can feel him soften inside me).

Ive been told that masturbation as well as simply changing positions can help. The masturbation thing i think does help, but our schedules are super wack and usually we dont have much time to really plan out our sexcapades. Not to mention, he isn't put off perse on sex, he just doesn't have a high sex-drive to begin with(which is why i consodered it may be something medical or health related as hes 21 and im 20), which is why we don't have a lot of sex to begin with between work, school and his libido in a world when we were fundamentally living together, one extending their stay at the other's apartment, we have sex more often, but thats maybe only 3-5x a month? But when apart (most of the time) im lucky if i get him in the bedroom 1-2x a month.

On the position's note; we mainly do missionary or doggy. I ride him soemtimes but typically he cums faster that way. We arent huge people but neither of us are "fit" and he has a slight beer gut while i have a fat ass, so we dont experiment with positions too much. Any suggestions would be welcome.

The next thing i am considering giving a go about asking him to try is,, horny goat weed supplements? But the internet is giving me mixed reviews- not to mention it doesnt sit right with me to attempt to medicate the problem before trying to "train" the behavior out of his penis, but we feel like were running out of options.