Don't stress about it right now, but do take a breastfeeding class, if you haven't already done so. The most important thing to focus on wll be proper holding a latch.
Yes, it is possible for milk to never come in. My breasts also never grew...I am on week 24 of my 3rd PG, and I am still awaiting this glorious rack I have dreamed of my whole life. I haven't been successful BFing either of my kids, but I pray this time will be different.
There will be some moms on this site who will tell you that EVERY woman can BF, and thank God that almost all can, but there are true instances of insufficient milk production due to insufficient mammary tissue. Hope and pray that you are not one of these, don't stress about it in the meantime, but in the end, if the milk never comes, don't beat yourself up about it.
My 4 yo and 18 mo were both formula fed, both are very healthy with no sign of allergies.
Best of luck to you!!