impotence

  I'm having a problem that I'm ashamed to discuss with anyone.
  I'm 25 y.o. and have been impotent for about 6 months now.  I've never had this problem before and don't know if its physical or mental.
  My last girlfriend really shamed me sexually because of my penis size and ever since I can't function.  I don't think its physical, I don't have any other symptoms and am on no meds.
  I'm about 3 in. flacid and 5 1/4 in. erect and since my girlfriend laughed at me and told others about me, my problem started.
  I don't know how to get past this.  
  Any advice?
Dear JoeK,
The causes of impotence are multi-factorial and consist of psychological, hormonal, neurological, systemic diseases, drugs, and arterial (structurally related entities.)  From what you describe, you have secondary impotence--i.e. you were once able to sustain an erection which was suitable for penetration.  What I would focus on is what happened during that period of time when your erections/ or quality of erections changed.
Do you have spontaneous erections when you awake?
Can you stimulate yourself to have erections?
Is there any bending/curvature to your penis?
You sound like there may be a definite psychological component--i.e. performance anxiety.  The comments your partner makes about her dissatisfaction with your performance does not make the situation easier and may be the root of the problem.
Your penis size is not the cause of your impotence because you functioned adequately with the size in the past.  There are surgical methods for penile lengthening and augmentation, however, this is considered experimental, especially in healthy individuals.  These procedures are wrought with complications which include, but are not limited to,  infection, penile deviation, sexual dysfunction, painful erections, poor cosmetic results.
For more information on the surgical complications, reference The Journal of Urology Vol. 155, 1617-1620, May 1996
This information is provided for general medical education purposes only. Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition.
Sincerely yours;
HFHS M.D.-JL
* Keyword: impotence/ penile augmentation