Need help to see how many weeks I am 🤨

I was wondering if any of you ladies could help me figure how many weeks along I am? Considering getting to a dr will be difficult for a few weeks or more with covid-19.

My last confirmed period was March 8-13 My usual cycle is always 26 days and always regular. I’m not on any birth control. My partner and I slipped up and I bought a plan b on March 19, Right around the time I would be ovulating. I crossed my fingers and my “period” came 8 days early, I was confused but thought I was in the clear because it was heavy. it ended a few days earlier than normal but I thought nothing of it, I spotted on and off since then which is not normal for my cycle but again didn’t think anything of it because plan b can do that I thought I was having a second period. The spotting ended.

last Thursday something told me to take a test and I’m definitely pregnant. I’m just confused with the timing. Am I 4 weeks or 5? The conception dates could be, March 17, March 30th, or April 1st. Did my plan b fail on the 19th or did it happen later?

Hopefully not too confusing any help would be great 😊