Oh man when do I know

(I didn't know where to post, sorry if you've seen this tw

My bf and I have been together for a few years and decided we wanted to buy a house together in the near future. As in, within the next 2 years. We both have a stable job, but aren't super comfortable financially.

Now I've been having doubts in our relationship every now and then, mostly because of these 2 reasons;

1. I'm quite young and never really had my 'messing around' phase. A boyfriend or 2, but no hook ups, no games while going out, etc. Most importantly, I'm bi and haven't had much chance to experiment with women. I would still really like to. Like, a lot. But now I can't. I've talked about it with my bf and even though he understands... there's not much we can do about it. An occasional 3way is the best we can do.

2. I don't always feel like he's the right person for me. We're very different in the way we look at the world, work, socialise, show love (love language), etc. I've been struggling with this and sometimes I don't know if I'm settling because it's convenient (we work together and live together, we like each other AND are always around), or if I'm really just overthinking our perfectly fine relationship due to past traumas. Maybe I could do better? (As in, find someone who's a naturally better fit for me, because my bf is an amazing person and it would be purely personal, nothing against him or for a lack of trying from his side).

And now we're buying a house. Which is a major commitment. We happened to have found a place way earlier than we anticipated, and I had hoped to have figured all of this out before we did, but I didn't. So. Yeah.

I don't want to tell him I don't want the house, it's his dream place and it would hurt him a lot if I said no now, especially if I explain it's because of these reasons. And I also do really want to live together. Maybe it's just the wadload of money that it's going to cost that is scaring me...

So... if you've made it this far, my question is basically; when do I know I'm making a huge mistake? Because despite my doubts, there's nothing realllyy major that is telling me to stop. Would it be fine if I just went along with it all and then just see later? Will it someday suddenly be easy to just end it, or will I just know this is it and we'll live happily ever after? Or am I signing up for a life of settling and looking back when I'm old with grown children regretting my choices now. And if I can't figure it out myself and HAVE to talk with him, how do I make it hurt the least?

I'm so overwhelmed, a neutral thought would be really appreciated, thank you!