Finasteride is a 5AR inhibitor. It blocks the 5-alpha reductase enzyme from converting Testosterone to DHT. DHT is not directly produced by the prostate.
Given the timeframe, I think your dermatologist is right. probably not male pattern baldness. Not DHT related. Nobody progresses like that in a month. Are you thinning in the back and on the sides as well?
Doesn't look like diffuse thinning to me. Its possible you have some very early frontal hair loss, but when your hair is wet and clumpy under a camera flash, and all combed away from the front of your head, this can easily make it look like you are thinning when you really arent. Talk to your...
I personally do 75mg. It's 50 mg/ml, and 1.5 ml covers the areas of concern for me. I get it from cheymo. Other popular sources are anagenic and thekaneshop. Keep in mind the stuff doesn't have safety data backing it up, so do your own research and weigh your risk vs reward.
Have you looked into Ru-58841? It will competitively bind with scalp testosterone & probably further increase your results. I have a peach fuzz outline of my juvenile hairline now from finasteride, minoxidil, ketoconazole, microneedling, RU. If you're really trying to max out your hair potential, a topical...