I am STUCK!!!

So, i am typically a thin person, I have been through about two spurts where I gained weight and weighed about 145-150 lbs and thats not including pregnancy. When I was in the army i was really bulky do to the nature of their exercises, they tend to make women look like men sometimes. Anyhow I am wanting to get down to about 110 lbs or between 115-110 and stay there. I am biking ten miles a day and alternating between abs and legs everyday for my muscle building. I usually eat less than 1000 to 1200 calories in a day and they are usually pretty healthy. Lately I have been stuck! I am stuck at 118-116.4 and no matter what I do I stay there. I take supplements, which i just switched, so maybe that will help, but it's hard to stay motivated when nothing works. So tell me your tricks because I'm dying to find something that will work