False Positive?

My husband and I have not been able to get pregnant in over 9 years of marriage. We have adopted 3 beautiful children and really haven't been TTC for 4 years. Because of PCOS we just thought it wasn't possible for us, but my periods have always been like clockwork. Not ever more than 3 days late. I am currently 8 days late and I took a test last night. I stared at the word "Pregnant" until it didn't even seem like a word anymore...

My biggest fear is that this is a false positive because of my cysts. I can't call my doctor until in the morning to see what we do from here. My question is has anyone had a false positive because of cysts? How common is this?