Feeling movement

Help a women out... I go from appointment to appointment okay then as one looms I get so nervous. So I'm nearly 17 weeks and haven't felt any movement yet and the more people ask me the more nervous i become. I will add it's my third baby and have some extra padding this time round. I also cannot remember for the life of me when I felt movement before 10 plus years ago. I do occasionally feel very heavy lower tummy when I stand...