How to make pegging easier?

So, I want to get pegged by my bf (trans ftm) but I struggle with taking the dildo he got me. It's either painful, too overstimulating for me or I'm too tight for it. Can you lot help me out at all? Give some tips or something? We try and make sure we use lots of lube but I still end up having these problems 😅 Anyway! Thanks for reading :3