I am no currently in week 24 too, i dont't always measure my tummy but i can feel my tummy is growing
just done my check up yesterday and gynae measure the tummy size and mentioned that is within the tummy growth size.
baby heart beat as per normal too. I think as long you go for your monthly check up, dr would advise you.
dont't worry too much and important things is must be have positive minds. Another things that i think tummy size does't mean anytihng, my collegue having a small tummy untill deliver but the baby came out with healthy and weighted 2.8kg hehehe,
I believe your baby will be healthy as you also eating well. Cheers.