Weird period?

My last period was just....weird

Normally, ill have my period pretty much on time (only been like this for the last year or so) and it'll be 3-4 days. And usually depending on how heavy it is obviously, ill use 3-6 pads a DAY plus 1 overnight

Well in December.... I had my first post m/c period December 1-4.

And then I was due for my next one December 31. Well I got it 4 days early, on the 28th.... except that it only lasted a day and a half-2 days. And I only used 1 pad on the first day, 1 overnight, and 1 on the second day....and never filled a pad.

It just threw me off quite a bit...

Any ideas?

P.S. don't think it matters...but now I'm getting faint positives on tests and based on my last "period" which would be the weird one on the 28th, I'd be 4 weeks today...

I thought maybe the 28th was implantation but my test results would be way darker by now if I was almost 8 weeks pregnant....