when did you start feeling the baby move and when did you start to show?

I'm 340 pounds and pregnancy has gone good so far! I'm 18 weeks and find out what the gender is this coming Friday. my appointment 4 weeks ago they had a hard time finding the heart beat and ended up having to do an ultrasound. the baby was completely fine and we got to see the heart beating, but that was one of the scariest moment ever! anyone around my size when did you start feeling your baby moving and when did you actually start to show?