Pregnant after miscarriage- was trying to prevent!

Ok so I miscarried back at the end of August and bled for 6 weeks. My period returned in October. I’ve been tracking ovulation to avoid pregnancy. In November my boyfriend and I only had sex 4 times and none of them were during ovulation to my knowledge. I had a short 2 day period in November. We have had sex twice in December but once again not during times I believed to be ovulating.

I was supposed to get my period on the 21st and it’s now the 24th and still no Aunt Flo. I took 4 pregnancy tests this morning and they were all positive.

I am baffled how I can be pregnant when we barely had sex and it wasn’t close to ovulation when we did! Is it possible I’m still picking up a positive from the miscarriage?? I am so confused and scared.