Negative OPT + Weight Gain

I’m typically EXTREMELY regular, exactly 28 days (I have Crohn’s Disease, so this has always surprised my drs, esp since I’m 5’6 and have usually been 95ish lbs). This month I’ve taken 5 OPTs and they’ve all been negative (since I’m so regular, I always get a positive on my OPTs within a day or two of when I start testing). Additionally, for the past week or so I’ve been putting on weight pretty quickly, I’m up to almost 103...it’s been about a pound every 2 days! Is it possible to gain this early if I were preggo?? Similar experiences?? Just odd things for me.