Feeding and formula milk. Not filling?

Hello. My baby is 25 days old. I breast feed her. But she is never content. After every feed of half hour she cries badly for milk again within 15 minutes . Is her stomach not filling? I feel I have enough milk. When I press I can see milk coming out. Also doctor has given me tablets and granules for producin more milk. It's been 8 days now am taking medicine to produce more milk. Still my baby ask for milk all time. I can't feed her for 24 hours I get tired. Can I supplement with formula milk at least 3 to 4 times a day along with breast feeding other time so that her stomach fills. Also she passes stools almost 10 times a day. And urinates almost every half hour. Doctor told to feed strictly at 1 to 1.5 hour interval. But that's not possible cause she cries a lot and doest stop until I put her to breast. Please suggest me some solution.