2ww = two week wait, refers to the period between ovulation (after the shagging) and before your period/possible test date.
DPO = days post ovulation
OPKs = ovulation prediction kits. You pee on a stick and it tests for presence of LH (Lutenizing hormone) which tells you you're about to ovulate in the next 48 hours. Bit fiddly to use. Less accurate than BBT (Basal body temperature).
BFP = Big fat positive (pregnancy test). BFN = Big fat negative.
AF = Aunt Flo (aka period)
CD = cycle day
Usually with the apps to recognise miscarriage you have to input the pregnancy and then report that it's ended. But you can just start from cycle day 1 as though it's a normal cycle, too. I find fertility friend is the best one, most of the others are too gimmicky and not very good for actual data. Fertility Friend looks very 90s but it does work and has good info. I'm too stingy to pay for the pro version and the free one is fine, though I'm sometimes tempted.