Keep in mind that the diagnosis of premature ejaculation is based on self-assessment. The average time it takes a man to ejaculate during consistent stimulation is 2 minutes or less. That's why it's important to have foreplay, start and stop if you feel you're getting too close, and really pace yourself. If you've always prematurely ejaculated, then you may need to practice kagal exercises to strengthen your pelvic floor. If you used to have duration, and now you don't, then it can be a result of a change in your body's health status.
Anxiety and a hypersensitive sex drive are often due to a lack of grounding. I don't think the solutions are going to be found in western medicine, you need to look at more eastern sources like tantra because they understand the energetic basis of this. When the root is weak, spontaneous emission or premature ejaculation is common; and when the root qi weak, it cannot hold down ascending qi, which rises up and causes panic attacks. Meditation where you sit on the ground or focus on your feet and your connection with the Earth can help. But usually you need to strengthen the root qi with diet as well. To put it more simply, you need to find time to disconnect from activities that require thought, and make time for practicing the absence of mind, and with calm, and peace.
From my own personal experience, I have found that bodily deficiency or exhaustion leads to an imbalanced sex drive (ranging from hyperactive to underactive), and ejaculation time is affected as well. I suggest you look at your body as a whole system. Anxiety and serotonin depletion are considered deficiency states. They are symptoms of a more root condition.
You can try eating more mineral dense foods, and foods that contain what is esoterically known as "essence": seeds (sunflower, pumpkin, sesame), bone marrow broths, etc. Make sure you've got magnesium, calcium, and all the B vitamins (especially B12) covered in your diet because a lack of these can lead to nervous tension. Pumpkin seeds are an especially important source of zinc which is needed for prostate health.
I personally have found the herb rhodiola excellent for anxiety and depression. It supports healthy energy metabolism but kills cortisol at the end of the day, something you may need. I'm not sure if it balances one's sex drive, but it does balance adrenal response. I've also read that it reliably increases serotonin levels in the body.
One herb I've used in my practice for men with hypersensitive sex drives + hyperactive/anxiety states is American ginseng. It is a calming adrenal herb that restores reproductive vitality, in a way that cools the body.
ebola? is correct about SSRIs... they would ease your anxiety and probably cause sexual side effects that prolong the pre-ejaculatory phase, but I don't consider SSRIs as effective as food or supplements that could replenish a deficiency that is causing the imbalance.
