I'm freaking out!

Ok so just a little info about my cycles, they are irregular or what I consider irregular, I get AF every other month like every 40-54 days or longer. But every time AF arrives it last 4-5 at the most 7 and it starts out heavy with cramps and then light. But this time I started oct. 28 and it started out light with no cramps and on the 5th day which I thought wa going to be the last I started cramping bad and it got heavy, so I figured I would stop around day 7 we'll no I didn't it has now been 18 days of bleeding and today it started getting heavy again with a few clots I have an appointment next Wednesday with an gynocologist but I'm worried this has NEVER happen to me.Please give me some advise!