15 Month Old Not Sitting Up, Crawling, Holding Bottle, or Walking...?

My daughter Kyrstin is 18 months old. She was born at around 27 weeks. So "corrected" age is 15 months .... she has been in physical therapy since she was released from the hospital at 3 months old, and with twice a month therapy she has come a long way. She was so fragile when we brought her home, on several meds and on a apnea heart monitor, my husband and I where scared to touch her she was so tiny. When we brought her home from the NICU she weighed just under 4 pounds. She did not hold a bottle until around 8 months. She did not start sitting up unisted until she was about 13 months old, crawling at 15 months, taken off the heart monitor at 17 months and she has been walking on her own for about 2 weeks. She still has some problems when she gets going fast or "trying" to run, but she is getting it. She does not talk, only babbles...the basic ma-ma and things but she waves bye-bye all the sudden...It seems that the past in the past 2 months we have seen her totally bloom. She is starting speech therapy in Oct, they tell us that they can only do one thing at a time (learning wise)...like 1st she will learn to sit up, then concentrate on crawling, then concentrate on walking then talking that sort of thing. I know that it is hard, and you worry to no end at how she will do developmently. And when you see another baby your babies age it only makes you worry more. All babies are different and all preemies are different, have you spoken with your pediatrician? Our pedi is awesome and gave us some information for Early Childhood Intervention (ECI)...they are a state funded program BUT they will see anyone. If your income is above guidelines there is a small copay that you will have to pay, but nothing huge NO matter what your family income is they will see you. We have the best group of people working with Kyrstin. I wish you the best of luck and I know that in her own time she will start to do all the things she is (supposed) to do.....until then work with her every chance you get. We spend A LOT of time "playing" with our preemie princess.. Good Luck and Blessings to you and your family.