Around other stars there are probably billions of planets that we haven’t found yet. It seems likely that almost every star formed some planets, so if there are 100 billion stars in the Milky Way, and even only half of them have planets, that’s a lot of other solar systems!
The smaller the planet, the harder it is to find, so we can’t actually discover systems just like ours yet. We can discover planets like Jupiter and Saturn, but ones like Earth are just a bit too hard right now cos they’re too small and not very massive. In the next ten years we will hopefully start discovering true Earth-like planets, and then we’ll really be finding how many other solar systems there are.