I understand what you mean. I started at 19 and it was aggressive as hell. Unfortunately, stress has nothing to do with it. I guess you could just go to a dermatologist or a GP and hear what he has to say. If he prescribes it, then that's it, if not then your search continues. There is no way to find a dermatologist or GP that cares for hair. It's not like they state on their sites "We care for your hair." Go and see, trial and error is the only way.
And yes finasteride helps tremendously in keeping what you have. Believe me, you need it. As you live in the states, you can buy Minoxidil foam without prescription even at the Wall Mart. If your doctors do not want to prescribe finasteride, you can get on Min without their permission. Keep that in mind, you can take control over it by Min, but I would favour finasteride because it actually tackles the issue at its roots, i.e. androgens.
Good luck and let us know how it went.