Nervous about quitting my job!

This is one of two jobs for me, I got this job expecting to be full time. The manager that hired me told me I would be getting 30+ hours a week, but I have only gotten 5-10 every week since then. I went to her last week and told her I was forced to pick up a second part time job, and she got really rude with me and scheduled me for every day that I asked to have off for my new job...she even scheduled me for my baby shower! I'm going to go to the main manager tonight and put in my two weeks notice. I can't afford to only make $60 a week with a baby on the way. I got more hours in two days at my new job than what I make in a week or two at my other job. I'm just nervous about quitting for some reason... Wish me luck, ladies and gentlemen.