That would put you on CD20 (cycle day 20). Do you know how long your cycles usually are, before they got messed up? Let's assume you have a 30 day cycle. Most women ovulate approximately 14 days BEFORE their period. That would mean you O'd around CD16. You would not be able to test until CD26, given this scenario.
I would guess that no, you are not pregnant. Oh, one more thing. Was the period you had a "regular" one? I'm just thinking that there's a chance that if it was very light, possibly it wasn't a period and actually implantation spotting, which usually happens around 7-8 days past O, I think.
Have you been diagnosed with PCOS? I really think you need to find a different OB/GYN. Yours does not sound very "fat friendly"...especially since you are no longer fat!
Hope this helps and didn't confuse you more!