Struggling with the change during the first week.

I made a decision back in September that I needed to make a change. I've had a gym membership off & on for almost 4 years but really started to utilize it a little over a year ago. I'm currently 70lbs overweight & I'm just tired of being out of shape. I invested a lot of money in a personal trainer & it was embarassing & hard the first few sessions. But it's been worth it because I'm more confident in the gym when I go on my own. On the flip side, I have greatly struggled to get my eating habits in line. I knew I needed to cut calories & make better food choices. My eating habits were affecting my progress in the sense that I was working off enough calories at the gym to maintain my current weight. So I felt stuck in the same place. My trainer had given me the information to this site, but I kind of set it aside & forgot about it. After months of not making progress & my mom hounding me to join weightwatchers, I decided to give this a try. So far, I'm very impressed with the site itself. Love how easy it is to track your food intake & workouts. The thing that's really hard for me this first week is the massive calorie drop. What the site has calculated for me is very reasonable, I'm 5'1 & given 1440 calories per day. Plus, I like how they give you the back calories based on what you burned during your cardio workout. However, this week was very difficult for me to get into the gym, I have a 3 year old daughter & work (4) 10 hour overnight shifts. So I've been doing good the last few days & sticking as close to the 1440 calories I'm given, but I feel like I'm ALWAYS hungry. My meals are between 300 & 450 calories, & I snack on really low calories foods inbetween. But I feel like I need to eat something every couple of hours. It's not really discouraging, but it's frustrating because I have a hard time keeping myself full. I don't plan on going back to my old eating habits, I just need for my body to adjust.