We weaned our daughter at 16 weeks, as she wasn't fantastic at drinking much milk. She was brill when she 1st had solids.
It's so hard when you're a first time mum (like you say regarding conflicting advice) but I honestly wouldn't hesitate about weaning at the age again if I was ever to have another baby. Years ago, babies were weaned much earlier than that.
No advice with a prem baby but maybe wait just a couple more weeks? Good luck. Remember to take some pics of her. We filmed our daughter eating her 1st solids.