I need primal some expert advice.

I have been primal for about 2 years. Before primal, I weighed 180lbs (5'11). Going paleo/primal, I went down to 170lbs in the first month. I still had weight to lose, but could never go any lower. Recently, I was traveling a lot and had to eAt out more than normal. I gained 5 lbs. the problem is, no matter how strict I am, I cannot lose this extra weight. Ive been trying fir 5 months. If I cut out all fruit , grains, legumes I can slowly creep down to 173. Whenever my weight it gets to around 173, it always then Jumps back to 175. So basically now my weight is between 173-177. If I eat out and still avoid sugars, breads and stay moderately paleo, I will balloon to 177. Is this related to high sodium content in restaurant food? In my lighter days I would make 'primal desserts', but recently stopped those as well. I do drink lots of coffee with trivia - my only indulgence.

I haven't tried IF seriously yet, so that might be next. Any ideas or tips to explore