Hair Thinning, Anxiety. Had Eating Disorder. Taking Prozac. Suggestion?

Hello, I am a 21 year old female who has been experiencing persistent hair thinning for the past three years. I have a history of an eating disorder but have been eating healthy and have overcome the disorder since three years ago. In college, I have been taking Prozac for anxiety and am under the average amount of stress regularly any pre-med student experiences. I run/workout frequently and eat very well but I am still noticing overall thinning of hair and receding temples/frontal hairline. There is no family history of baldness/receding hairline. Thyroid levels and iron levels recently checked and normal. Dermatologist did notice hair on top two-thirds of hair 30% thinner than hair near neck. I have always had very thick hair growing up and now there is not any evidence of new hair growth, just constant thinning. Dermatologist recommended Rogaine for Women, but after two months I saw no improvement, but continued hair loss . It s also very expensive on a college budget. He said hair loss due to stress but I feel like I manage my stress very well. Any more advice? Could it be a hormonal problem? It s frustrating to constantly hide the thinner spots when styling my hair in the morning. I m only 21 this shouldn t be happening.