Zara,
I am so sorry for your loss.

I haven't given birth, but only m/c. But I know that you won't ovulate while you still have the hormone (HCG) in your system, and that it needs to return back to normal levels to trigger the ovulation cycle.

My dr advised me to have at least one normal AF following the m/c before TTC again.

I have used OPK sticks, and found them quite good at helping me determine when I ovulated. You can get them cheap on ebay.

once you ovulate your period is always 12days later. No matter how long your cycle is.
half right - each woman will have a fairly standard luteal phase (from ovulation till menstruation), and it is "around" two weeks on average. Mine is 11 days. If your cycle is longer than usual then it is usually because the ovulation is delayed.
A great book is taking charge of your fertility by Toni Weschler.

I wish you all the best, and hope you get your BFP and forever baby soon.

much love,
Milly