Hi, fellow lap banded and future RD. I sympathize with your struggle. I lost 115 lbs and have rebounded almost 25% with a unhealthy rapid gain of 12% my UBW in 3 months.
There are not established energy requirements for bariatric patients - at least no one agreed upon measures, though there are practitioner or article specific ideas. Calculate your basic energy requirements using an online Mifflin St Jeor calculator. You should never go under 1200 calories a day without a significant medical reason or supervision by a healthcare practitioner and definitely not at your height. The basic way to estimate protein requirements 0.8g x kg method. (kg = lbs/2,2). Unless you are under physical stress, such as when you had surgery these needs might be elevated a bit but 0.8 g is the DRI.
Consider seeing an RD who takes your insurance for really tailored educated energy requirements, especially since you are concerned about a specific macronutrient. Try to find one that specializes in bariatrics (search through ZocDoc or get a referral from your surgeon), as she make understand the weight rebound common with Lap band patients, have creative, targeted strategies for LB patients and also recipes that are Lap band friendly.