How do I convey this to my partner?

So my boyfriend who I've been with for roughly 3 months and I became intimate almost immediately but our sex has manly been vanilla and we're bored. He's a hardcore and experienced dom and super into BDSM. I have lots of fantasies about BDSM on the opposite spectrum, (submissively) and I have so many wants that have to do with being tied up, being degraded, and generally overall masochistic type things. However, I'm really inexperienced and he wants to do all these things but I get scared and start having extreme anxiety and actually a lot of fears about how it will make our relationship awkward and I'm really scared to tell him the things I desire even though I know that he won't judge me and and will probably even be thrilled. Uuuuuugh please help me.