What Causes Weight Gain, Puffy Eyes And Fatigue?

I have slowly been gaining weight. My eyes are puffy all the time. I am tired. I am an active 46 year old women with two teenage boys. I work full time as an officer manager at a law firm. I work 9-10 hour days. I never stop going, but the three factors I mentioned above are constant. I have had the basic blood work to check my thyroid, but it was normal so they did not go any further. Just because the basic thyroid test is normal does that mean that it still could be my thyroid. I was low on vitamin D and potasium and am now taking additional supplements other than my multi-vitamin. I try to sleep 6-7 hours a night. I snore alot and wake myself up constatly. Any advice.