They don't usually expect you to count kicks until like 26 weeks since baby is still pretty small. You're probably just not noticing them if you've been busy.Baby could have moved into a new dspot as well, and may not be able to kick the same spot as before, making it feel not as strong. If there is movement, baby is fine! I'd just bring it up at your next appointment if it's a big concern for you. Some moms don't even feel baby moving yet at 20 weeks. It all depends on baby's position, mom's awareness and a ton of other factors too.
Are you doing kick counts? They'll probably ask when you call. Just a heads up. Agree it's probably ok as long as you're feeling movements.
Sure everything is fine, but called midwife or get checked x