Can’t Deep Throat after Tonsillectomy

I used to be able to deep throat almost anyone but since I had my tonsils out (it’s been a year and a half) it feels like I hit a wall when I try to fit him further down my throat. It used to be one of my favorite things to do and a skill I prided myself on but now I just get frustrated. I’ve been able to do it a few times but I end up thinking about it to much and loose my rhythm. I’ve been dating my boyfriend for a year and suck his dick a good amount. I still don’t gag and feel like it may be scare tissue or I need to stretch it out again but it was something that came naturally. Any ideas on how to stretch it safely?

I have asked a few friends and heard that deep throating was easier after they had their tonsils out.

Thanks!