Feeling nervous...

Ja

I’m 18 weeks tomorrow and have yet to feel any movement from baby. This doesn’t worry me too much because I know for a first time mom it can be 20 weeks or more... however, I have like no bump. I have definitely gained weight in my stomach but it is not a defined bump. People can’t believe in nearly 20 weeks pregnant when I tell them because I am fit and slender and have no bump... I’ve gained about 5 lbs is all. Should I be worried?