Abnormal sleeping

My 2yo has been like that since she was born.She never slepped through the night or her naptime.I have always waking up more then 5 -6 times at night to go to her room and calm her down.wjen she sleeps her noon naptime,usually its about 1 hour or more.Sometime its even lasts up to 2.3 hours.BUT-she wake up afet 20-30 minutes of sleep screaming and crying,and if I want her to continue sleeping a little bit more,I have to take her with me,either to my bed,or on a couch,just to be near her when she is sleeping.I have been doing that for 2 years now,and I am exhausted!!! At nights she wakes up several times too,crying and screaming.Lately I just stoped going in her room,I just let her cry it out and go to sleep again,but I deffinately go in if she cry more then 7-10 minutes,to check on her.I don't think that this is a normal sleeping pattern she has-a child should sleep! And she doesn't really! Our PD said that this is normal,and she is that kind of a baby who doesn't like to sleep...
I suspect that she has some kind of a dissorder,that makes her waking up screaming at nights.Maybe we should see a PN(pediatric neurologist)?