I am sorry for your loss. I can tell you from my own personal experience, it's not easy and very hard to get over. I've had 3 miscarriages - two in one year - one at 20 weeks and the other two at 12 and 16 weeks.
We TRIED EVERYTHING to get pregnant the first time - 4 years of TRYING. No kidding, tests, needles, etc. Literally two months after we just "GAVE UP", we got pregnant. I wasn't EVEN THINKING about it - the stress that TRYING to get pregnant created in my life, on my body and in our marriage was HUGE. Giving up was a HUGE RELIEF and the fun came back! KABOOM! Preggers!
I can tell you that after my first miscarriage, I was pregnant the next month. I was NOT even thinking about getting pregnant again. After the second miscarriage, I got pregnant again 3 months later.
The problem you are having is called STRESS. Stress has EVERYTHING to do you with you being able to conceive (and produce milk) - your body feels the stress you are under and will not allow you to conceive. It's like the "flight or fight mode" your body is fighting you right now.
Take a deep breath - grieve for your loss and don't think about getting pregnant again - once you take that stress off you, you will be amazed at how your body will react! Stop charting and all that other stuff - you are creating excess stress on your body. Relax, have FUN sex, not the planned timing sex - it really takes the fun out of creating a new life.
I hope this information helps you. I would beg you to stop charting and stressing over this. You cannot replace the loss of one child with another. Grieve over your loss - it's a healing process and your body will acknowledge that.