Help, should I tell my bf I’m okay with bottoming

I’ve asked him what position he thinks he would prefer (we r both virgins) and he says he doesn’t know and it’s up to me. Not to shame him but he is scrawny, has barely any stamina, is shorter/way lighter than me and mf has health problems. I worry that if we did ever take any further than touching and he received his body will NOT be able to handle it that being said I can’t tell if he is saving face and wants to please me instead of telling me what position he really wants. I want to please him but IDK if I should let him know that I worry about him receiving it and that if he really wants to go all the way I’ll offer my… . Tbh I’m not that into sex in the first place so I want to do what he likes but this shit is embarrassing as hell I don’t know where else to ask lmao.