Progesterone and procardia question

Ive been on procardia and progesterone since 27 weeks when I went into preterm labor. Every FFN test has come back negative. Just had another one yesterday and it came back negative at 34 weeks. Both babies have been head down for 9 weeks. They have not been doing cervical checks. I guess im getting kind of worried the longer I stay on these meds that the bsbies wont come naturally on their own. Anyone experience this and questioning what point to stop. My 5'1 frame is having a difficult time and I could def do 2 more weeks but by 37 I would want them to come