For the flight, I would definitely get yourself a moby wrap or similar stretchy wrap. It will be a lifesaver when it comes to calming and soothing your baby, and will mean you can actually use the toilet when you need to and have your hands free to do it. If you're BF, you'll be sorted. If you're FF, I would probably opt to bring formula with you so that you keep the brand the same and don't go switching around, which can cause tummy upset. If you are feeding formula, I'd bring sterilised bottles and those cartons of ready made formula for the flight. I wouldn't bother trying to mix up formula on the plane or in the airport. You'll be able to get all your baby supplies - things like wipes, nappies, etc. there - and I'm assuming you know the area you'll be going to well enough to know the best places to shop, so I wouldn't really bother about bringing any of those types of supplies, beyond what you would need for the flight, unless you're really picky about what brands you use.
I might also pack a few snacks and things for yourself for the flight. At that age, your baby will mostly just sleep and want cuddles, so won't need much entertaining. But if you're busy comforting him/her or changing a nappy or doing whatever at meal times, you might not get much time to sit down and eat, especially since you're travelling alone. I'd just make sure you have a few things with you to eat or drink in case you don't get much time to eat at meal times. You can make up for it later.
Also, I'm not sure what you've thought of yet in terms of weaning onto solid food, but I would definitely wait until you get back to start solids. 6 months is the recommended time to start anyway, but I know some do start at 4 months. I wouldn't risk trying to wean while traveling, being in a strange place with strange foods, where there will be bacteria that your baby hasn't been exposed to before, besides just the hassle of them having to prepare and pack food wherever you go. I'd leave it til you get back, which sounds like it will be right about 6 months anyway. Good luck! Where are you going? My husband and I used to live in Pune.
