Dear
Welcome to HCM
We understand your concerns
I went through your details. There are many potential causes of DE, including psychological hang-ups, chronic health conditions, and reactions to medications. Relationship 
stress, poor communication, and anger can make DE worse. Disappointment in sexual realities with a partner compared to sexual fantasies can also result in DE. Often, men with this problem can ejaculate during 
masturbation, but not during stimulation with a partner. Medications such as antidepressants, antipsychotics, 
high blood pressure medications, diuretics, and alcohol can all cause DE. In that sense, 
Zoloft could be a cause. But you should talk to your 
psychiatrist.
If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR.
Make sure that you include every minute details possible. 
Hope this answers your query. Available for further clarifications.
Good luck.