I am sorry, for some reason the # of days blanked out. I know that on a 28day period, I usually start trying on cycle day 11, but not sure on a 21 day. Have you tried an ovulation predictor kit? Discharge can be a sign of pregnancy, or a sign of upcoming ovulation (amongst other things). Good luck in trying to conceive, I wish you well.
Well get an ovulation kit for sure.....and discharge could be alot of things. GOOD LUCK and keep us posted on how you are doing!
OPKs and BBT can help you to pinpoint the best timing for trying. Discharge can guide you as to when you O but it's not very reliable. Many people have clear discharge around O but also before AF.
Good luck!