ETA - By the way, Aileene is referring to the Ferber method (not Gerber- that's a mis-type.) She's right - Dr. Ferber explains that babies need to learn to self-soothe. And the mom who mentioned swaddling has a good point - your child may not be too old to swaddle.
Original:
The mistake you made is allowing it to happen in the first place. You should have kept putting the baby down without doing more. Now she's upping the ante because she's used to it and she wants more.
Time to stop doing this. She won't like it. But you either do it or continue being a human pacifier, which she DOES NOT NEED.
Start putting her down after nursing her and she's full. Sit down in the floor and put your hand through the slats of the crib and touch her leg. Don't talk, don't pick her up, don't engage. Let her cry. She will know you are there, but you aren't going to give in to what she wants. She will finally fall asleep. Do it every night until she stops crying. If you give in ONCE, she will know that crying works and she'll do it even more. You need to be 100% consistent.
Your baby is not a newborn anymore. She doesn't need to be held all night and suck on you all night. You CAN let her cry. You need to let her learn to self-soothe.
Put her down during the day and let her nap. Your 2 year old needs to stay in his room for quiet time, whether he sleeps or not.
T., it really sounds like you let your children run your household. Maybe I'm wrong, but your 2 year old should not be dictating whether or not your baby naps. Time to toughen up, mom.
Good luck,
Dawn