sex positions

anyone feeling like you're not doing enough during sex or if you just suck at sex? i have sex with my boyfriend & i end up quiting because i end up thinking too much if it's good if it's not good or if im trying so he'll love it.. idk how to even explain this couple days ago i was ontop of him he was playing his game he wanted it so did i ,i kept going & it felt like he wasn't enjoying it.. he told me he was & i guess i was too distracted with the show i was watching that i ended up stopping i asked him if he wanted it he said yea i asked him are you sure he said yes i asked him if he was enjoying he said he was so i said it doesn't look like it cause you're not hard anymore he said i am but you stopped you gotta keep going up & down cause i am enjoying it (the up & down thing was a joke) i got off bc i felt like i sucked at it which i always think i suck at sex. i lost my virginity 2 years ago got pregnant same year & have no clue what to do during sex idek when i cum when we are having sex only if i play with myself besides that i suck at it, i don't even take my clothes because i feel so ugly i rather have him not see anything even though he's seen me naked but when we have sex i dont like taking them off because im overweight not a lot just chubby so everything moves when we have sex & i feel so grossed out i dont wear lingerie anymore... i dont know what to do during sex i try sometimes to change things but even still i never know how to put my hands or what to say...