Maybe it's not an option for you, or you wouldn't be looking for advice here, but have you considered just enjoying it while it lasts? The pain of losing your son must be always with you, and exhausting. Plus you are a full time student? Wow--I'm impressed. I bet at your toddler's bed time you just want it to be BED TIME. Day done and over for her so that you can have some peace and quiet, some study time, or some plain old adult along time. If you are feeling on the brink of frustration to the point of anger, than you need to look here to advice and find a way to get this just, with NO guilt, ok?
But if not, if you're just feeling, hey, she's 2, enough already? If that's the case, grab a book and a book light, snuggle in and tell her to go to sleep. Personally, with my 2 year old, I use my laptop. She's got her sweaty head burrowed in my head right now. It's the only time I allow myself to "waste" time on the computer talking to other Moms (such as it is!) I have 7 older kids, and before I came in with her, I spent time with the next youngest my 8 year old, helping him brush his teeth, washing up, dressing for bed, getting him positioned, reading a chapter of another installment of "Weird School" to him before hooking him up to his BiPap for the night. The other six do put themselves to bed. And all of them were going to sleep on their own eventually. Some by the time they were 3 or 4, some not until 7 or so. But not a single middle schooler asks me to snuggle up with him or her. And rarely does anyone older than 11 ask for or even readily accept a hug or kiss, much less a snuggle.
I hope this helps you a little. Whichever route you go, trust your heart. I'll be thinking of you. K.