hi big

i know what it feels like to have your body behaving in a very strange way.
going back to the doc is a very good idea,unusual bleeding needs to be evaluated. ask for some blood tests ie quantitative BHCG and a hormone profile.
quant BHCG(this is important not just a BHCG) will give you a number (not a pos or neg). if the answer is anything but 0 than you are / were pregnant.
so for example if the number is say 25, if another quant BHCG is done 2 days later and the number increases (hopefully doubles) things are looking good for a pregnancy. if the number decreases than it means you are having a miscarriage sorry

The hormone profile will give you answers as to just where you are in your cycle(on that day). ie pre/post ovulation so you can work out just when your next AF is due. once you get these results (tell the gp you want a copy) if you want help interpritating them just post again and me or one of the other lovelys on BB will help i'm sure

what you are going through is very similar to what i went through at the beginning of the year.
my AF was due on the 11 jan ( i had been tracking my ovulation trying for #3 for 18 months, i always ovulated on the 11/12 day of my cycle ) i had decided not to track over xmas and just assumed i ovulated on the 27 dec (wrong).
no AF on the 11 jan(very excited did test next day BFN)
bleeding on 13 jan (normal day 1 for me, quite heavy
bleeding slows than stops on the 14th jan
17 jan come out of bedroom busting out of a sundress DH says " are you pregers your boobs are huge !!" i say i can't be i had my AF 4 days ago"
25 jan i have vague symptoms (other than the big boobs, but nothing major), do another test ( middle of the day, not first wee of the day) BFN
3 Feb after dropping DS at first day of school i decided that either i am totally psycho or am pregnant BFP .
i had a dating scan at 12 weeks from my LMP but was only 9 weeks + 5 days. so they think my bleed was at ovulation, i think otherwise i think it was implantation. my EDD is the 10 oct (i think 3 oct).
so yes our bodies do some strange things, we don't always ovulate on a schedule.
goodluck finding some answers it's what you want.