Almost 7 months old and has not met milestones?

My little girl will be seven months old July 29. She was only three weeks early but seems to be delayed. I took a lot of medication while I was pregnant with her because I have a child at 28 weeks at the start of the year.(All medication was under doctor supervision) When I took her to the doctor in May her head measured around 38 cm. When we went back a month later for her sixth month check up her head measured around 43 cm. The doctor wanted to watch it because it was such a jump( less than the second percentile to above the 75) We have also noticed that she has never rollen over. She has trouble holding her head up, she will not sit up even with support she just flops foward. Also, she will not put pressure on her legs, also she does not scoot. She will make eye contact, smile, and laugh. Also, she does not babble or coo. She does not respond to her name most of the time nor does she respond to no. If you have any ideas or things that I might need to talk to her doctor about PLEASE let me know. She has an appt today at 1:40.