I know what you are going through. Me and DF had been TTC for 3 years. I'm 35 and he's 45 so age wasn't on our side, and added to that DF was really ill last year with an ongoing condition that could have affected his fertility.
Anyhows, I'm now 9+3 and all is going well.
The stress and pain of those 3 years though was awful. Especially in the first 18 months. After 2 years I went to my GP and had my bloods done to check I was ovulating etc and all was fine so we decided to carry on for another 12 months and if nothing happened we'd pack it in.. I'd already decided against any invasive tests or treatments and as my periods were like yours (ie clockwork) I assumed I was ovulating regualrly.
As I wasn't going to have another baby (I have a DD aged 8 from a previous relationship) I put a deposit down on a new horse.
Lo and behold, AF was late, I was constipated and had sore boobs so did a test and got my BFP!
I put the problems we were having down to not DTD on the right days. I had looked on the web and charted when I thought I was ovulating and for 5 days before we DTD every day. By the 6th or 7th day neither of us could be arsed. Because that particular month we hadn't bothered DTD on any specific day 2 days after I thought I had ovulated (therefore too late according to my theory) we had sex. I think that is when I caught.
So my advice is to 1) put down a deposit on a v.expensive baby horse and 2) don't worry about when the web and the books and the little pee sticks (did them too!) tell you to DTD, do it whenever the urge takes you lol.
If you have had a MC (sorry for your loss) you can fall pregnant. Obviously that bubba wasn't meant to be but the next one will, according to the statistics be a sticky baby.