K.M.
I am at the end of my 3rd pregnancy (only 6 weeks to go!) and I can tell you that nothing about this one was similar to my other 2. Nothing! I felt movement much earlier, had back pain earlier and that heavy feeling in the pelvis way early. It was almost like my body was saying "oh yeah, we already know what to do" and the muscles just sort of flopped back into place from the previous pregnancy. With 1st, 2nd I carried very low and tight. This time through I am way out front and high. Nothing to do with gender as I already have a boy and a girl and they carried the same.
So what you experiencing is pretty normal, at least from my experience. I also had that heavy feeling low because the baby was sitting in the birth canal and facing my spine. It made me feel things differently. This one also has a different sleep/awake cycle than the other 2 did. My others were super active and punched and moved constantly (even in their "restful" times). This one is more sedate and just does more rolling movements and has definite times of rest where I feel very little movement for a few hours and then it is awake and plays for awhile. Usually when it hears its siblings!
Good luck with #3! Should be an experience.