Flying with baby

My husband and I will be traveling from Michigan (Flint) to Florida (Fort Walton Beach) the first week of February. We are visiting my parents, my mom is in hospice in end stages of pancreatic cancer and she hasn’t met her grand daughter. This will be her first and only time seeing her. She will be 12 weeks. Does anyone have any advice? The first flight is 2 hours 20 minutes with a layover in Atlanta for 2 hours 30 minutes and then the 2nd flight is 1 hour 14 minutes. (I’ve taken this flight many times and it’s usually always way shorter). There we leave at 5:50pm ET and get in at 11pm CT. On the way back we leave at 6pm CT and have an hour layover in Atlanta and get back to Flint at 11:15pm ET. We are flying Delta, and she doesn’t have her own seat, just in our lap. She is formula fed. And a rather tough baby. Colicky and reflux, (but hopefully those will be improving by then). Any tips or pointers? I’m planning on taking her boppy on the plane. We need a car seat and stroller and have a chicco key fit 30 with a Chicco cortina stroller. Do I need her birth certificate? Can I take bottled water through security if it’s sealed for formula? What’s best for her ears feeding her while take off/landing or pacifier? Does she get her own carry on? (Diaper bag) or is it counted as mine or husbands carry on? Any other tips or pointers to try and make this as smooth as possible? I’m super stressing since she’s hard just at home. lol but my husband and I are a good team.

(It’s also an hour drive to and from the airport in Michigan and about 15min in florida)