Most Helpful Girl
This is not ED but the way you start worrying, you are on the right path to getting it.
It is understandable that you worry that you could stay hard but at this stage this not ED. You were probably just too nervous to do something wrong or not to do it correctly that you made yourself a mental blockage. This in turn impacted on your erection. Being a virgin is also adding to the blockage that you want all to be perfect. The first time is seldom perfect.
ED originates in the brain and develops when you have an ED on several consecutive times. You start developing a fear that you cannot have an erection when you need it and you end up in a vicious circle.
You think subconsciously that you will have an ED and the brain transforms this anxiety into reality.
Go back to bases 1 to 3 and go about the last steps in slow increments. Take your time and if you have the chance to have a girlfriend that can help you with a HJ or BJ before the actual intercourse, you will not want to come down from 7th heaven and your ED fear will be a thing of the past.
Enjoy every second of this first time and don't let your brain take over and tell you what you can and cannot do. Good luck!