18 weeks baby movements

Hi mummies! I am 18w 2d to be exact & this is my first pregnancy. Yesterday was the first time ever that I felt my baby’s movement like gentle tap & wriggling quite a lot of times through out the day, even when I was taking a nap. I was so happy! But today, i don’t feel anything at all. Is it normal that sometimes baby’s movements come & go? #advicepls #firsttimemama