I think it's a great thing to donate eggs . Having been through IVF myself to conceive 1 of my children, you come in contact with women who are unable to fall pregnant using their own eggs. Many have been through years of treatment, heartbreak and loss using their own eggs and to get to the point of considering donor eggs is huge. To help people in these situations is a wonderful thing.
The needles are tiny and if you are quick and don't hesitate - you'll be fine.
Your biggest hurdle is your age, because at 20, you may feel done now - but realistically you have another 20 fertile years left. A lot can happen in 20yrs and I guarantee you will mature as a person and you will change your mind on many things as you get older. Because of this, many clinics will have reservations about your suitability as a donor at this point in time.