i had this trouble for the longest time too! they seem to go through periods of this and it is usually after a water change (they like the nice clean warm water!) and once i started feeding them bloodworms (they were on those boring pellets for a while before then). i find that having enough places for the female to hide seems to help, and since i never really noticed her tryingt o struggle or affect her appetite i didnt worry too much. i am however considering getting another female for the tank to try and take the pressure off her. hope this similar scenario helps alleviate your concerns, cross your fingers for tadpoles, so much fun!