Sounds like your pregnancy is going like mine did. I am also pregnant with my second, but I am almost 6 months along.
Like you, the first trimester of my first pregnancy was uncomfortable - nausea, tiredness - but very manageable; this time, I have had days exactly like you describe. With my energy level way down, when I had time to spend with my daughter, I had to lie down and just let her play around me. There was about a two week period when, from the moment I opened my eyes in the morning to the moment I forced myself to shut off and go to sleep at night, my nausea was so strong I had to really focus on not vomiting. I had to force myself to eat because I knew I should, but nothing tasted good. There were periods of time when I had to sit very still because any movement made me feel like I would be sick. The thought of possibly feeling like that until delivery would make me want to cry.
The more dramatic body changes I can relate to also. I've been wearing maternity clothes since about the second month. My doctor reassures me that it's just because everything is already stretched out, and it's normal to feel extra "flabby" (that's her word!) in subsequent pregnancies.
The good news is that right at the end of my first trimester, it was like a fog was lifting. I was so focused on making it through each day, I didn't even realize how badly I was feeling until I started to feel better. To say that it was a relief doesn't come close to describing how I felt! Now, although I'm still more easily tired and feeling humongous, I feel SO much better.
I know it's tough to dread every day, but hang in there...you only have a few more weeks until you should start to feel much, much better!