Decreased movement

I went on Sunday for an NST after I called my dr and said the baby wasn't really as active as she has been. I passed the NST just fine. Heartbeat was good and she was kicking. Monday I hit 30 weeks and each day I feel like her movement decreases a little bit more. I don't want to keep calling them about this if it's nothing. Is this normal for them to decrease In movement significantly around this time? I also have a lot of pressure in my low abdomen/ pelvic area.