Please help me get out of my head?

So I’ve been dating my bf for a month now and he was my first ( kiss, time having sex, time having a guy sleep over, oral, etc..) and as prior knowledge we dated once before in high school and we essentially broke up because I had feelings for another guy (his friend) and I had been flirting with him and he told me he kissed my best friend (when my bf and I hadn’t even kissed yet) even though they didn’t actually kiss.

Now to my current issue. Now that I’ve finally become sexually active I feel like I wanna experiment with other people but I know me and even if I wasn’t in a relationship I know I wouldn’t do it.

Also my bf mentioned he, with a previous girlfriend, had a miscarriage and he doesn’t wanna talk about it and I don’t even know what girlfriend it was but it’s always in my head

And I feel worried like I might have feeling for his friend still (that he’s still really close with)

But I just feel so lost in my head and I don’t even know what I’m confused about but I just feel weird about everything but I know I don’t have urges to seek out someone else to be with, and I love him very much but my mom hates him and his family and doesn’t think we’ll work out and we probably won’t in the long run and I’m not gonna lie he’s not very attractive and I’m more physically attracted to other people but I’m not attractive enough to be with other people because I’m so overweight and I’m also terrified that I’ll end up pregnant somehow.

I just feel so overwhelmed and I don’t know how to handle it so, please help.. anyone?