Losing motivation, looking for advice

Hi everyone!

I began trying to lose weight seriously in October, and since..using a healthy diet and exercise, I am down around 30 lbs. I stick to a 1200-1400 calorie day (I am eating healthy, just to clarify) and have been going to the gym 3-5 times a week, as well as doing work out videos at home when I get the chance (Zumba, TurboJam, Yoga). My gym routine is always the same...either 45 minutes on the treadmill at 3.5 mph and a 10% incline, or 45 minutes on the elliptical at level 10

Here is the problem...I am stuck. I can't get beyond 157 lbs. It has been this way for weeks now. I am still busting my butt and not seeing any results.

I have been given every piece of advice imaginable...do weights, do intervals, work on what I'm eating. Curious to know what the mfp community has to say :) Thanks!