I would recommend bringing it up to your doctor. Most likely its due to hormones in which case they can maybe prescribe something to even those out. But i feel ya on being fat, tired and just ready to be done. The heat doesnt help much either.
Hi I feel exactly the same way yesterday my manager suggested I start my mat leave early due to my snapping at my other colleagues very grumpy and tired hoping it will pass very soon! I have mainly been concentrating on thing I have to look forward to, to get me threw the crappy times