I've said it before and I'll keep saying it: with an infant, you NEED to carry-on 24 hours worth of ALL supplies that are necessary to keep the child nourished, clean and content.
24 hours worth, always. TSA may tell you it is too much, so remain scrupulously polite, but stand your ground. Ask for a supervisor if necessary. TSA has *no* control over airline operations, and they have no way of knowing if your flight(s) are likely to be delayed or stranded on the runway. It is ENTIRELY possible that it may take up to 24 hours to reach your destination, even if your flight is non-stop and short.
I've been there and done that. I've traveled extensively with children, and I've been caught short before I learned my lesson. Airport stores don't normally sell formula or diapers except in international terminals, and when they do they sell one brand, which your child very well might not be able to eat. They don't sell infant food, either. Neither do airport-hotel gift shops, if you have to take an overnight layover due to weather or a ground-stop. Planes do not stock baby supplies or even (except for long haul widebodies) cow's milk. You also do not want to depend on the aircraft having enough bottled/canned water to mix formula -- bring it on board yourself, either by buying it bottled or bottling it from an airside tap at the airport. (And bring extra -- you haven't known thirst until you've been sitting on a hot runway for 8 hours in an unairconditioned aircraft with a nursing baby!)
My recommendation is to avoid carrying glass if you can -- it is heavy and prone to breakage. (If you have to, pack the jars in baby's socks.) Go with the Gerber plastic food packs if possible, and the pre-mixed 8 ounce plastic bottles of formula. (They last longer when opened than powder-mixed formula does.) You CAN bring ice packs to cool formula; you just have to declare them with everything else. For convenience, you should probably fill one small softside cooler bag with all of baby's feeding needs, and label it so that TSA can immediately see that it is all for the baby.
Lastly, if you normally use powder-mix and need to use premade, or vice-versa; try your baby out on it before you go. Some kids will balk at the difference in consistency.
About diapers: FA's serve food, and because of that they are not allowed to touch used diapers. (Most of the time they are not allowed to hold babies, either -- even briefly. Liability insurance issues.) Unlike a previous poster, I've been on plenty of narrow-body aircraft that had no changing tables. While you might be able to change a newborn on top of the toilet seat, or a toddler who is standing up, most of the time you will not easily be able to do it inside the lav. The best technique is to carry disposable paper changing pads (the kind that hospitals have), and change the diaper on the floor directly outside of the rear lav door. You also want to carry sealable plastic bags to hold the used diapers/wipes. Keep the lav door open with your foot so that you can reach in and dump waste into the toilet without letting go of the squirmer. Seal up the used diaper junk, put baby back together, and dispose of the diaper in the lav trash. Wash your hands initially with a diaper wipe, then (if you can) take baby back to your seat and hand him over to someone else, and then go back to the lav and wash up properly.
Changing a baby at your seat is generally considered a rather nasty faux-pas. However, it has been my experience that if it comes down to smelling a soiled diaper for an entire trip, or witnessing a quick change, most people will go for witnessing the change. Obviously, only do this if the seat belt light is on and the FA (or the pilot) tells you that it is going to stay on for a while. You want to make it fast, and contain the smell immediately. Apologize to nearby passengers and tell them that you would get up if you could. Don't use the tray table. Lay the baby across your lap with his legs facing the bulkhead, and if you are not traveling alone, have your SO help you deal with the details, like handing you the clean diaper and bagging the soiled one, and with holding down the baby so you can get the change done quickly. When you finish, bag the diaper and changing pad in plastic, then put it in an airsickness bag, which you will hold on to until you can get up to dispose of it. Wipe down the entire seat area with fresh diaper wipes, just to make it clear that you care.