firstly keving id like to say, good on you. Good to see your taking action and oging in the right direction by seeing a dermatologist. o recoment you see multiple dermatologists jsut to be sure. Before you go and see a dermatologist i recomend you get a blood test, to see if your health has anthing to do with hairloss.
Health can play a big role in the quality of your hair. Secondly you may want to get a 'skin biopsy' on your scalp. Im not sure if a regular doctor can do this or a dermatologist is needed. The derm may just examin your scalp and could tell if your have male pattern baldness. also note. Do not bother with a triologist, they are not doctors DO NOT WASTE YOUR TIME.