Condoms make my vagina dry!?!

Okay me and my boyfriend have been together for a while. I’m on the pill but we still used condoms as a backup. Sometimes we’ll start before using a condom then then we stop and put one on. And sometimes we start with it and sometimes we just don’t use one. But I’ve noticed that everything we use a condom any wetness that I had goes away after like 30 seconds and after that it doesn’t go back at all we just have to stop because it so uncomfortable for both of us. Like I’m 21 I don’t get why this is happening I have an appointment with my doctor but it’s not for 2 weeks. We haven’t tried lube yet but has this happens to you? We use Trojan condoms.