Am I going to the gym enough, too little, or too much?

I'm a stay at home mom and i watch two little girls in my home during the weekday so i don't have a lot of time to get to the gym. So far this week I've gone 4 times, about an hour and a half each time. I start out on the treadmill walking at about 4 mph, at variable inclines (from 0 to maybe 2.4). I walk for about 30 minutes, then do some weight training on the machines. I do 3 reps of 10 on each machine, finishing my 3 reps before moving on to the next machine(5 second break between each rep to catch a breath). I then, depending on the time, either walk another 10 minutes or ride a stationery bike for 10 minutes, and maybe a few more machines. I used to go to the gym a LOT when i was in high school to the point of obsession: every single night, for 4 or more hours, which i don't have the time to do anymore. Lost 100 pounds in less than a year. I have quite a few pounds i'd like to lose from getting married and having two children in under 2 years. When i say quite a few, I mean 50+ pounds. I've also cut out sodas and am eating pretty healthy. Probably the worst thing i've had in a while was some peanut er i had on an apple slice. Please let me know if I'm working out enough, too little, too much. thanks!