Feeling tired again

This week I've started to feel tired again. Despite my official second trimester status, I feel (physically) as though I have entered the third trimester. The weight I am carrying is becoming cumbersome and the belly is turning into an obstacle. I have lost the will to pick up things that fall on the floor or are on the floor to start with. Also, I am having to make more modifications to my weight training regimen because my belly won't allow me to sit properly in the machines at the gym. Third trimester isn't until week 28 though. Lucy is not as prone to kicking me as much as Rebecca did, however, she is a big squirmer and her contortions have caused me greater actual pain than Rebecca's pushing, shoving and punching ever did. Also, Lucy is a definite night owl, and is most active when I want to sleep. Last night she did something that was so painful it actually woke me up.
My edema has definitely set in - I can see the compression marks when I take off my socks at the end of the day. However - it is certainly not as bad as it was by this point in my pregnancy with Becca. I think I can attribute this to the weather, since hot weather is known to contribute to edema. I am making a conscientious effort to do to what I can to reduce my edema, but I think a certain amount is inevitable. I have had a few more middle-of-the-night leg cramps, for which I am taking mangnesium supplements (above and beyond my daily multivitamin). Poor Greg is going to have a heart attack if I keep waking him up in the middle of the night with my shrieks of pain.
These physical limitations are as frustrating for me as when I am miserably sick. I feel like a prisoner of my body in certain respects. I can no longer put Rebecca into her car seat without considerable discomfort, so I have asked Greg to move it over sometime this week. Lucy's infant seat will go in the middle, and we need to install an extra bolt anyway - so the timing is propitious.
I am having a bit of trouble with my motivation in the workplace. This is due to a combination of physical and mental factors. My lack of energy, discomfort sitting in a chair for prolonged periods of time, and sore back make me feel like I want to be home, or at least somewhere where I can shift positions, put up my feet or take an afternoon nap. My patchy memory, fatigue, and anticipation of my maternity leave have sapped some of my enthusiasm for my projects. I have apprehension about whether they will be looked after when I am gone, and it makes me wonder what the point is.