Hiya,
Welcome to the boards.
My babies were born 12 weeks early and came home at 9 weeks old.
Are you having treatment for the reflux? Does she have any symptoms? I know not all babies do.
How much milk is she having and when? What happen when she wakes at 3? What do you do?
With developmental milestones, I use their adjusted age. Sam and Lydia both smiled at 18 weeks, so they were around 9 weeks corrected. I think I've got that the right way round!
I wouldn't worry too much about hitting the milestones - they are only a guide and every baby is different.
Lydia also had a hernia but it has corrected itself.
Don't beat yourself up about the guilt. You did the right thing for you and your baby.
We mums give ourselves too hard a time as it is!
Hope this helps.