Help!

I am so confused. My last period (always been irregular) started 5.14.17 and ended 5.18.17 and I haven't gotten it this month yet. I've had to push back my date 3 times on this app, which I didn't realize it also changed my fertility window and Dpo. So last week I took a couple tests and got vvfl on them. I've been waiting the 3-5 days to retest and today I feel like there's no line at all. Now that my cycle is screwed up, I don't even know my Dpo or anything! Anyone else going crazy!?