Thanks for the reply. Here's the answers to your questions:
1) no medications
2) about 4 years. Yes, I have no problem achieving an erection. I encounter one of two problems: either it goes limp after a few minutes into intercourse, or I ejaculate prematurely. The few times I have had an erection last through intercourse, I was pretty drunk, which seems strange. Also it should be noted I have fewer problems sustaining an erection through oral sex.
3) yes, I can achieve an erection through masturbation, but I have had the same results occasionally. I do seem to have problems with premature ejaculation even through masturbation sometimes. No nocturnal emissions or waking up erect, that I can remember.
No injuries to the genitalia. I have a family history of diabetes, but as far as I know, I do not have it.
I know my best option is to see a doctor. As i've said before, I don't have a family doctor. Should I see a regular physician or go straight to a urologist? When choosing one, do I just pick a name out of the phone book, or is there a research method I should be using. Thanks for your help, as i'm sure you understand, this has been a very difficult situation for me.