I used Dr. Oksana Lekarev in Cornell. She only accepts Hip; see if you are able to switch the plan or ask them if any other dr in the practice who takes healthfirst. Phone number to the office is 646-962-3442.
Dr lekarev is a very kind dr, but actually it seems as if everyone in that department is nice. Office has a pleasant atmosphere.
I recommend Dr Romero in Mount Sinai. I use him for poor growth issues. I don’t know which insurance they take and how long the wait is for an appointment but it doesn’t hurt to call. I haven’t used the other doctors in the practice, but I’m sure they’re good. The number is 212-241-6936. Good luck!