Some advice needed

[Millais]

I'm an 18 year old male living in the United Kingdom. I've been losing hair for roughly a year but only recently decided it was serious enough to do something about. I went to my GP and he confirmed I was losing my hair at the crown and on top; he did all the necessary blood tests and told me I was fine nutritionally and that he would refer me to a dermatologist (I have an appointment on the 8th). That was in January and I have since bought and started taking finasteride (18/2/13). I also started using Minoxidil (5%) probably around the end of February or the beginning of March.

However, I'm not sure how to continue with my regime. I'm not sure if the finasteride I'm using is genuine as I bought it from an online pharmacy that didn't require a prescription (http://gogettabs.com/) - lack of research I'm afraid - and it was produced by genpharma, which I've read mixed reviews of. I think I've experienced some additional shedding since around the time I started using minoxidil, which I'm trying to take as a good sign (difficult though that is), although it could just as well have been due to the minoxidil rather than the finasteride. So, do you think it would be worth taking the financial plunge (remember I'm 18 and so funds are limited) and getting some finasteride I'm sure is genuine from somewhere like ukfinasteride.info or from a pharmacy after I've seen the dermatologist and hopefully got a prescription, or should I just stick it out with this suspicious batch until I need to re-stock? Oh, and so far I've had no side effects.

Thanks in advance