100 mg is a medicine used to induce ovulation in women to help in conception. It is the right medicine for you to use if you are planning pregnancy
To answer your second question, Yes women who conceive once are more likely to conceive easily and again. Conception once implies that your ovaries and tubes and uterus
are relatively healthy and there is more chance of a pregnancy again.
however this time you may need a more monitored pregnancy with hormonal
injections and other medicines to take you through the entire 9 months.
Keep good follow up with your gynecologist.