Definitely add potato and/or some other root vegetables such as parsnips, swede etc. My daughter borrowed mine today to use up some leftover veg - red cabbage, sweet potato, red and green peppers and onion. But there wasn't really enough sweet potato (and it doesn't thicken quite as much as ordinary potatoes - less starch I think), so it was thinner. Not watery exactly, but thinner than she'd expected.
If you want a chunky soup, then you need more veg and less water, I'd say! Just keep experimenting. And look up recipes online - there are plenty out there.