I'm so sorry for your loss, and so glad that you are going to keep trying!!! I know that there are ladies here who can help more than I can, but this is what I know...
1) Condoms have a higher success rate than the pill, don't they? And you could always try charting to find out your fertile days... in order to avoid them! That's still no guarantee, but I think there are a couple of moms around here who conceived right after a miscarriage (Sam at least.. and x_ashley_x?) and they seem to be okay? Of course you should TRY to follow your doctor's advice... but if fate steps in, I don't think it's much of a reason to worry.
2) Never had an m/c, thank God... those who have should be able to help.
3) I charted for awhile... but it seemed like when I was charting, it never really workedo ut for us to B/D on the best days... DH would work late or something would come up, we'd have a fight or something and NOT be in the mood. After awhile I stopped taking my temperature, but I was semi-consciously aware of my cycle length, and we just B/Ded about every other day for the time period that would be aprroximately around ovulation... I may have missed an early ovulation or something, but I was a lot more relaxed after I stopped the really specific charting, and it was more like "Oooh, wonder if we can make a baby tonight?" Rather than "Okay, this is the day. Pants down, legs open, lets get this over with." It became more fun, and we actually B/D ed more often, and it was more fun. And it worked eventually! Especially since you've conceived already once, you know that you CAN... If I were you I'd relax and enjoy for a few months at least... be aware that "it's around that time" but don't worry too much about pinpointing the exact moment of ovulation? You're only 20 anyway... even if it does take you awhile, you'll still be a young mother and have plenty of time to have multiple babies if you want to.