Training 4x a Week due to Missing Period

I used to strength train 6 days a week: push pull leg repeat, but I lost my period. Immediately upon going four times a week, I got my period back. My concern is that with training only four times a week I will not be able to gain the same amount of muscle I was gaining when I trained 6x a week. Do you guys think I could make more "gains" during my four times a week split? Also, what are your split for those of you that do four times a week? Thank you!