tubal scheduled..but possible pregnancy???

So, this is weird. I was on the pill which shrunk my 33 day cycle down to the 28 day, got off of it because of side effects a few months ago, and had a period 28 days after that (CD 1 being former CD28). I had a bit of light red-brown discharge a 2 wks or so ago (splotchy memory). I was feeling grouchy and fatigued, so I checked the site to see what my CD was this month and it was 26- so I figured PMS and took primrose and that was it. But there were very light cramps for only about 10 minutes 1 day, and then a heavy cm since then. It's now CD35 and started having nausea yesterday. I've been pregnant before, and they didn't show until my 2nd missed period (which resulted in a MC for my 3rd since we didn't know really. I just thought it was irregular due to my IUD being removed.) Sorry, got distracted. Anyway, I'm just curious: will a blood test tell me if a HPT doesn't? I'm due for a tubal ligation on the 27th! That would be some funny stuff if I was pregnant again....
And another thing is, my nut allergy that I developed with a previous pregnancy disappeared, and I'm CRAVING peanut butter! WEIRD! Though it may just be a coincidence. (mind you, I couldn't even breathe near someone eating peanuts a month ago without feeling like I had inhaled chili powder.)