Twins born at 27+6 here, now 17. They were slow with their early milestones - rolling (Twin 2 didn't roll until 8 months and that was only once, only to be repeated about 3 months later). They didn't crawl at all (sort of shuffled), they wouldn't go on their fronts at all and didn't walk until they were 15 months actual (12 months corrected). Concerns about Twin 2's hearing but all OK in the end. They were signed off by the Paeds team aged 2.
Both passed for selective grammar school at 11, got mainly 8s and 9s at GCSE and predicted all A stars / As for their A levels, one applying for medicine at uni, the other has offers from top unis. Both sporty, happy, you'd never known they were premature.
I think I worried about it until they went to school - and when I had another (full term) baby and realised that they all do things in their own time (premature or otherwise!). Yes, you need some monitoring to start with, various checks etc, but with hindsight, I realise I was constantly comparing to other children, wanting them to get to next milestone, worrying they were behind which kind of stopped me enjoying them as babies. That's a completely natural reaction I think but try to enjoy your DC, try not to worry. Best wishes