Hello Chsami,
Online websites like Healthcentral.com are wonderful resources for getting information to help you ask all the right questions when you see your doctor, but they can not take the place of your doctor's sound medical care. Here are some links to information that will help you ask the questions of your doctor to help.
You have quite a few topics here, so I will try to get you links to all of them.
You mentioned premature ejaculation. You can read about premature ejaculation here. There are some listed symptoms and causes. There is also a section here about prevention and treatment. Although there is no real prevention for premature ejaculation, there are some suggestions here. Dr Owens at Sexualhealth.com also had this to say about premature ejaculation, "Meanwhile you can masturbate, if you want to. This is a very good way of improving your erections, and there are several exercises you can do in order to lengthen the time before you ejaculate. You can read about these exercises on our page dedicated to rapid ejaculation or in the chapter called "Developing Ejaculatory Control" in the book, The New Male Sexuality by Bernie Zilbergeld. I can highly recommend this book to you. " You can read the rest of the article here.
It sounds like you may be experiencing an orgasm without getting an erection. The Harvard Health Publications group posted an article here about men who have orgasms without erections. You can read the full article here.
Lifestyle can affect your erections too. Smoking, drinking, conditions like diabetes, high blood pressure, medications for various conditions, there are many many things that can affect your ability to get and keep an erection. This is why it is important to see a physician to make sure there isn't something medically wrong.
You can read about erectile dysfunction and some of these causes here and check your symptoms here.
I hope this information helps somewhat. Please stay in touch and let us know how you are doing!Vicki M