Follicle of 20 mm. size is considered adequate for ovulation to occur. Follow your gynecologist's advise and ask for a follow up sonogram to know the rupture of the follicle. Having a single miscarriage
is not a negative point in future conception. This happens with many couples who go on to have uneventful pregnancies later. As your husband is also on treatment he may be asked to have a repeat semen count after three months of treatment. Please get further advice from your doctor. Good luck.