I found the latter part of the 1st trimester, and a few weeks into the second trimester hard with a little one (she was 20mths when we got pregnant with #2). There would be days where i would lie on the couch all day, watching hi5 with my daughter. I felt so guilty, lazy, stupid, but it was all i could muster. My DH was on a rigourous course for 10 weeks, mon - fri and studying on weekends, so i really didnt have a break. I didnt suffer morning sickness, it was more exhaustion, tiredness.
I can honestly say, as the pregnancy wore on, i got bigger, and the EDD got closer, i had more energy, i enjoyed my time with my DD, and i actually enjoyed the pregnancy....