Calculations

Okay so first let me tell you my periods are highly irregular. My last period was from April 18-22. The cycle before that was 37 days(which is a low number for me.) I supposedly ovulated May 15-21. I got my BFP yesterday! :) but I took another Clearblue advanced digital just to see my weeks calculation and it says I'm 1-2 weeks, which by Doc terms they would tell you 3-4 weeks. But counting from my last period I should be 7 1/2 weeks. I've heard ppl say the 1st 2 you aren't really pregnant but would I still be about 5 weeks today? I'm so confused and I haven't been to see the doctor yet since I just found out yesterday.