Having kids and doing grad school is not a bad decision at all. Just hang in there girl! Awwwh! Please don’t feel guilty about leaving her with a Baby sitter. That’s the right thing to do in your case. You are doing good, if she is sleeping less that means she is growing up. May be it’s something in the surroundings that irritates her, may be the crib or the sheet she sleeps on. Check for the irritants in her room/ crib. Have you tried playing some music, while trying to put her to sleep. Try it, it works.
Good luck!