how do I bring up the sex thing with my S/O?

So my boyfriend and I are both 16 and have been together for six months starting tomorrow. our relationship has a lot of trust and we're always super open to talking about anything and trying new things. I've definitely had the birth control talk with my older sisters and mom more than once, so as far as that goes, I'm pretty educated and aware of how to have safe sex. because I feel like our relationship is ready for this kind of thing now, I sort of want to start talking about it with him and see what he's okay with/isn't. like I just want to ask him if he wants to try oral sex or touching and see how far that takes us, but I have NO IDEA how to bring up the conversation. we're super open and I'm comfortable around him but for some reason my mind goes completely blank whenever I want to talk about it. as far as we've gotten in our relationship, we've casually made out a lot and he's even asked me to get on top of him while we kiss. also, he hasn't necessarily sent me nudes but he's casually sent me a handful of racy pictures before. however I still don't really know if he's ready for the sex thing yet, and I have no clue how I should bring it up with him. does anyone have any advice they could give me? thanks so much xoxo