31 Weeks pregnant and still have not felt much movement..?

Okay, so I am a little over 31 weeks pregnant. First off just so you are clear, I am asking for advice from personal experiences, because I have spoken to the doctors about this, before you say to go to a doctor. This is my first baby, and I hardly feel movement. Sometimes I do, but its not strong, actually its very light and I can go days without feeling movement. I go to all of my appointments and always mention this and they say everything is fine. Normal heart rate and all and I always measure properly. I had my mid pregnancy sonogram at 20 weeks and have also had a couple sonograms after, I actually just had one at 29 weeks, a couple weeks ago. Everytime they say the baby is measuring great and the baby is moving all over the sonogram. I am so paranoid that I go to the labor and delivery room almost every week to check and the same thing every time happens, they say I am fine.(I was actually just there yesterday again). They always do a bedside sonogram and put me on the monitor but she is always normal. (its a little embarrassing because they know me so well by now for coming in and there is NEVER a problem) Has anyone else had this issue where they don't feel their baby move? the doctors don't know exactly why I don't feel her but they always try to convince me that she is perfectly fine. I believe them, but then around 3 days later I'll worry again until I see a doctor. I do have a fetal doppler I rented and always hear the heartbeat but still get nervous. Any advice? Thanks and sorry for this long post =]
No, you are not rude, I have heard that also. But I was around 135 lbs when I got pregnant, and am now about 170 (yes, I am always hungry lol) but I am not sure if this effects the movement or not.