Confused, My Period Is Late, BFN

First off I already have two daughters, so I do know some about pregnancy :) HOWEVER I originally had PCOS (since age 15) so I am used to my periods being irregular. Since I had my oldest daughter in 2006 I have gotten my period every month (on average between 25 and 35 days). It was the same after I had my second daughter too. We are not using any type of protection, we are trying to conceive. Now here is my problem, I am over 3 weeks late (right now my cycles on average are 30 days). And for the first two weeks I took pregnancy test which were negative even though I thought for sure I was pregnant. When I first missed my period I had pregnancy symptoms, the cramping, bloating, feeling ill, tired, etc. This being the 3rd week I have not yet taken another pg test (I don't want to get my hopes up), but I do plan on testing next week but I don't feel like I'm going to start my period. I do tend to ovulate at different times because of the PCOS and with my second daughter I didn't find out I was pg until around 2 months. So does anyone have any ideas? I just don't know what to think!