HELP! I don't know what I am doing wrong!

I need some ideas on how to get off this yoyo I'm on. I have been on this yoyo with my weight between 129lbs & 135lbs since I lost 25lbs on Nutri-System 3 years. I am 5'2" & my goal is to get down to 118lbs. I eat very healthy & work out 2 to 3 times a week & drink lots of water. I just turned 60 in March & started using MFP hoping something would show up that I was missing. I have been keeping very good tract of everything I eat & logging all my exercise in as well as trying to do 10,000 steps per day but I still am on a yoyo between 130lbs & 135lbs. I can't seem to get past that 130 mark!