sex help...

So my boyfriend and I barely have sex as it is... but the past two times we have he's made me do all the work... and I don't mind pleasing him and I'm getting satisfied to but I get so tired and can't make him cum because I can't keep going. Like the one time he was drunk so I think maybe that was why he couldn't get on top so I don't think he cared he didn't get off. But we just did a few days ago in the morning and he wouldn't get on top he just left it at me getting off. (I usually hop off and pull him to get on top so he knows when to) and again I didn't make him cum I felt bad but he kept kissing me after and he NEVER does that so I assume he didn't really care. It's also hard for me because I'm 29 weeks tomorrow so again I get tired and it's kind of hard to get around. I haven't talked to him about it which I know I should but idk how to bring it up because we've never had an issue with having sex.