You cant just lift as much as you can every day and think it's going to work... Rest is about as important as the workout itself.

I agree with DFD, machine weights arent good. What you may want to try when doing situps is take some weight, put that in your hands behind your head, and start doing situps, you will definitly feel the burn alot quicker.

Buy some protein powder to make shakes, preferably of Whey protein.

Just one more thing, Eat breakfast like a king and dinner like a pauper.
Meaning that it's better to take the larger meals early during the day. Diner should be your smallest meal of the day. Besides diner dont eat anything in the evening.