Hi C.!
I flew with my then four-month old daugther the end of January for the first time. I had her on my lap and I had the same types of concerns you do and she is also a very laid back happy baby. We did a round-trip then and then again in March. I fed her a bottle on take-off and landing and gave her a binky like you said you planned on doing and just had a bunch of travel toys to keep her interest. She looked around at other passengers a lot and smiled at them and laughed; that kept her interest as well.
She'd been teething so I gave her a dose of Tylenol a few hours before one the flights and then another just before we left. She slept at least half the time on all flights and one of them she slept about 90% of the trip (it was an early a.m. flight, 5:30). But I didn't do that for every flight and sleeping on the plane didn't mess her sleep schedule for bedtime.
I think you'll be okay as long as you have things to keep her interest.
Oh also... there are NO restrictions from the airlines on bringing breast milk or formula on the plane when you're traveling with a child. I had a little soft cooler with 3-4 full bottles of breast milk each time I flew. As long as you tell them about it and show it when you go through security, there is NO issue. If you want to read about Traveling with children, go to www.tsa.gov and write "traveling with children" in the search box and it will bring up everything you're allowed to bring with you.