All THREE of those medications affect serotonin.
Please see the following link:
http://www.rxlist.com/drug-interaction-checker.htm
You need to clarify this combination, or better yet, get a second opinion, and the next time a pharmacist expresses concern, I would hold off on starting the medication until you can clarify it.
I'm confused. Is this a psychiatrist or a general doc? Given that your pharmacist has already warned you not to do this why did you do it before seeking a second opinion? Wellbutrin and Effexor are both stimulating antidepressants, so if your main problem is anxiety these aren't usually the solution; they might be if your main problem is depression, which is often the case with anxiety sufferers. Combining two drugs such as Effexor and Celexa that both target serotonin is very unusual, as your pharmacist has already warned you, and Effexor also targets norepinephrine, which is basically adrenaline. Wellbutrin is usually only combined with an ssri such as Celexa if certain side effects are present, such as low sex drive or weight gain. The usual response to a drug that doesn't work is to taper off it slowly and try another, not add other drugs to it. You only add drugs if the first drug is working and you want it to work better. It appears you have a simple situation of Celexa not being the right drug for you. You need a different doctor, preferably a psychiatrist who understand how to use these meds.