14 weeks from today 2 March would be 24 November so you'd already have been pregnant when you had sex on 23 December.
Going by the 16 November start date, you'd have been near peak fertility on 29 November when you had sex, day 13 of your cycle. You normally will ovulate between days 11 and 16 of your cycle, timing is perfect.
You can have bleeding that "mimics" a period while pregnant. Usually it is lighter and there are less "clots."
Looks like the first guy. Hope it helps.