Hi guys
I wanted to reply, but being young I don't have a whole lot of expexience that is relevant to you, sorry. My first thought would be to go to the fertility clinic and get some fertility investigations done... I had them done and was only 20 at the time, found I had PCOS and was not ovulating so needed extra help. I think its definately worth having it all looked in to, that way you don't waste any time doing home inseminations if you need extra help too.
As far as getting the donor tested, if you mean STD/HIV etc a trip to the GP is fine, if you mean testing his sperm I *think* thats best done at the clinic (don't quote me, we used an unknown donor so really don't know a lot about that part of it).
Good luck and I hope you get your BFP quickly!!!!!