Dr. Called-Beta Question

oxymoron1

I just got a call from my Dr's office with my beta level. I had it drawn one week ago today and the level was 3,213. According to my LMP I was only 4 weeks and 3 days pregnant. The nurse told me that according to my level that I was 8 weeks pregnant last week. I'm so confused. Beta levels are a new thing to me, so if anyone can help explain this I would appreciate it.

I know that I can't be 9 weeks (now) pregnant. Within that time frame I'd had multiple negative pg tests, an HSG, and my normal every 28 days period. I go in next Wednesday for an u/s. 

Anyone have any suggestions?