Starting to panic about motherhood

Baby girl is due Jan 12 and originally I was going to be a stay at home mom and work on finishing grad school. My sister lost her part time job a few weeks ago but luckily was able to get a full time job starting in Jan but that left her with no childcare for her 4 and 2 year old so we decided that I would watch her kids. I'm now freaking out about having my first baby, taking grad classes and being a nanny to her children. I can't not take the classes because we count on the financial aid to pay the bills and she can't not work. In some moments I feel like I can do it all and others I just worry that I won't know what the hell I'm doing. :( I guess just need to get through the first couple months and see how it goes from there. To think I thought my biggest worry for January would be taking a math class 😔 Just feeling overwhelmed and baby isn't even here yet.