Always too dry 😕

So I've been away from my boyfriend for 5 weeks and a month or so before I left, I would always get too dry when we would have sex. But While I was away, I would get super wet really quickly just thinking about the things I'd wanna do to him when I got back. At first I thought I was dry because we were rushing, but now idk?? I just got back home and we took our time building up when we were about to have sex, and when it was time I was still dry! I was dry the entire time. I tried using my spit as lube, but it didn't last and it would eventually hurt as he kept thrusting into me. This is so frustrating! I used to never have this problem and I don't get why this is happening. I've been thinking because I take birth control is why I've been so dry. Can anyone relate? I need to know what I'm doing wrong.