Hello AF: my cycles are getting closer, now just 21 days

I'm so frustrated. Starting about 3 months ago, my period starting coming earlier than 28 days when its normally pretty predictable. But now It usually starts with some really light spotting that gets my hopes up for implantation bleeding before kicking me in the gut and going for a full flow 24-36 hours later. Periods are more painful too. I was on birth control for like 15 solid years. We've been trying for a year and its starting to get depressing. I have a fertility clinic appointment next week. I was hoping to not need it. :(