Lack of libido and erection issues

Basically my situation is that I am a 23 year and I have noticed a decline in my sexual libido to the point where if I do not look at porn or have any stimulation in the presence of a woman I simply won't get an erection.  I could probably go for months without getting an erection if I don't look at porn.  I know for the past 2 weeks I have not looked at any porn or been around a female and thus have not had an erection or any sexual desire at all.  I do not feel depressed.  I am on a healthy eating diet, not over weight, and I do cardio 3x a week.  I also take vitamins, fish oil pills, as well as herbal supplements like Tribulus that are supposed to be known for increasing libido.  I also used to be on SSRI's 4-5 years ago and Wellbutrin specifically a year ago.  I have not been on anything since then though.  

When I AM with a female, I typically don't have any problems getting an initial erection, with foreplay and what not I can usually get a pretty hard erection nearly every time and when receiving oral sex I pretty much can keep it the entire time as well.  When I am having actual intercourse (always with a condom) however, I would say that 50% of the time I will lose erection if I do not manage to ejaculate within the first 5mins.  If I were to stop to change positions I would most certainly lose an erection.  When masturbating by myself I am able to keep an erection the entire time that I am looking at porn but if there is any disruption or break in me looking at it like needing to go to the bathroom then it often begins to weaken.  I have seen a doctor before about my testosterone levels and it apparently is normal.  Would something like Cialis help my problem?  How do I get a higher sex drive?  Even if it is a psychological ED what do I actually do to fix it?  I already know about "not needing to perform and just have fun" but that hasn't helped.  Why can I keep hard during oral sex but not vaginal?  What should I do?  

[Stephen Liroff, MD]

The fact that you can maintain your erection in some situations indicates that the mechanism does work. The problem is most likely emotional and definitely worth seeking professional help. The longer these emotional issues remain, the more difficult they are to resolve.
There is not a drug that will treat low libido given that your testosterone level is normal. Cialis and similar drugs are not the answer. You should consult a sex therapist.
S.A.Liroff, M.D.