Julie put it well... the actually act of conceiving should still be left to you & DH so meds that regulate your hormones & assist you in ovulating aren't off limits. It might be worth mentioning, too, that certain methods of semen collection for semen analysis would be immoral too b/c it removes the "seed" from the marital act. I'll go into details if you wish
Also, just a word of caution with "Catholic" docs... I know many that prescribe bcps, do sterilization, do IVF, etc. which are definitely contrary to Catholic teaching so I think it is always best to be informed of the treatment you choose medically & morally before agreeing to what
any doctor says.
Thanks Kara for the links too... this is info we could all use!