Help!

So this is the first month of using the Patch and how everyone made it seem was their were 4 patches then you have your period the fifth week so before I got the patch, which I started it on March 30th, I calculated that I wouldn't have my period until after prom. I completely forgot to redo it once I got the patches. But I was just thinking about it I only get 3 and I'm on my second one then I get my period the week of prom(April 23rd). I'm panicking because I've never had a period on the patch. Does anyone who has used the patch know how bad the periods are?