I am not sure about laying on your tummy but i am around the same as you time wise and have felt bubs on and off, i had my scan yesterday and everything seems ok, good size etc.

I think it's only a worry once your feeling them every day and then they stop for more than 24hrs, hope that helps and GL with the rest of your pregnancy.

Maybe ring the phsyio and ask them if they have an upright chair etc they can do things on, i got a pregnancy massage the other day and OMG it was amazing, odd looking chair and position but it was wonderful.