We've just flown for 33 hrs, plus to and from end airports, with DS 5 1/2 months. It all went surprisingly well. :)
Tips:
Pack everything you have to show at security in one of your hand luggage, together in one bag (eg light fabric tote). Computers, ipads, liquids etc. Then only one of you has to faff getting it out and packing it away, while the other has the baby.
Pack everything you want with you in your seat in a tote inside your hand luggage. Easy to get out and put at your feet as you get on the plane (or if you're in the bulkhead/bassinette seat, after take off). And easy to access and keep together in the open top tote.
Not sure why you think BF won't work next to a stranger. Worried DC will kick, or prefer not to show anything yourself? It is so much more convenient, not having to worry about bottles, sterilising, temperature, security checks, etc. Take a shawl or cover and go for it. If they're uncomfortable, hopefully they'll ask to move and you get more space or DH can come and take that seat. I'd be exploding if I waited that long...
DS is exclusively BF - but I had two single serve cartons liquid formula and a squeeze pack smoothie in hand luggage- just in case. Showed at security - no questions asked in all three airports (ARN, LHR, SIN).
DS was good for descent on first flight, fussed on second and third. Tried BF-he wasn't interested. We alternated dummy, finger and bottle of water to suck on. Bottle was a success - he only drank about 10ml, but it seemed to be what he wanted.
For mixing formula / heating, I suggest the cleanest water you can get (bottled if avail, otherwise the cold drinking water on the plane). Then use their super-hot stuff in a container around the bottle just to heat it. Less chance it will be too hot, and you avoid any concentration of minerals etc from their water heaters, which are probably never really emptied.
Read some of the other posts here about strollers and airports. Depends where you are - what is possible.
(eg: www.mumsnet.com/Talk/general_advice_tips/1278504-Help-We-need-your-tips-please-on-surviving-airports-with-babies-and-children, www.mumsnet.com/Talk/general_advice_tips/1284952-Want-your-buggy-delivered-to-the-gate-when-your-flight-lands)
Quiet toys - possibly new so they're still interesting. Taggy toys work great for us.
Take a blanket (we used a sarong) to put on the floor and let DC have a kick, roll around, in the boarding lounge.
Good luck! Sure it will be fine. :)