Orgasm difficulties

I have been on Zoloft 50mg for several months. I do not have problems with sensation or drive; I am still hypersexual and masturbation still feels good. However, I am having great difficulty reaching orgasm. I plateau, then start to approach peak and it just goes flat. Repeat. Repeat. Repeat. Eventually, I get there, after hours.

It is now near impossible to cum from external play alone. Internal play still takes hours but gets there eventually. But I am ftm trans (pre-T) and do not like internal play.

It is frustrating because I am otherwise reacting well to this medication.

Does anyone have any tips on how to nut faster on Zoloft?