I flew with my two many times when they were toddlers. It is really not bad at all. Here are a few tips:
1. Try to book seats so that one of you is sitting in the seat directly in front of her and the other is next to her (or just put yourselves one in front of the other is she will be a lap child). This way you do not have to worry about her kicking the seat in front of you and bothering a stranger. If you cannot do that, at least take her shoes off on the plane and then try very hard to keep her feet away from the seatback in front of her. Personally I prefered not to use a carseat for mine at that age. They rode more quietly when it did not feel like a car ride to them and the car seat pushes them so close to the seat in front of them that it is really hard to keep them from kicking.
2. Once past security pick up a bottle of a drink that you KNOW she loves and will want to drink (maybe her favourite juice). Pour it into a sippy cup (if you have one with a valve she has to work at to drink from that is even better) and give it to her for taking off and landing. The sucking and swallowing will really help her ears.
3. Pack snacks she enjoys. Think clean and easy.
4. The best toy you can pack for her is YOU. Just be there for her and on the entire flight. Help her explore the plane, the tray table, the sliding window blind, etc. is all pretty fascinating at this age. Even the barf bag is entertaining!
5. Also pack intersting things that she is not normally allowed to play with at home. Two favourites at that age from my kids were little post it notes and masking tape. They loved to scribble on the notes and stick them all over the tray table, windows, etc. The masking tape was just a sticky fascinating thing. They would unroll some, feel it, press it on the seat and look at the lint dots, etc and keep on and on until the entire roll was gone. A favourite toy and "lovey is good to being to.
6. Pack a change of clothes for baby and you in the carry on. Otherwise, do not pack a whole lot--you should not need more than one dieaper bag full of stuff for a 3 hour lflight. Too much too carry just adds to your stress.
7. Do not preboard. Wait at the gate (with your DD up and moving) until the last boarding call. No need to have ehr sit for longer than necessarry. At the gate play movement games with her like ring around the rosie, etc.
Avoid packing:
toys/books with sound effects
things that roll easily (crayons, markers, balls, etc.)
sticky things (sticky food, playdough, etc)