My cat attacks my legs when I walk past and I never know when it's coming.

What you are describing sounds like predatory play behavior that has been redirected onto you, which is very different from aggression that comes from fear or pain. The distinction matters because the approach is completely different. A two-year-old cat who launches without warning, with no hissing beforehand, is almost certainly operating in hunt mode rather than in defense mode. You are moving prey to her.

The reason it feels random is that cats in predatory arousal can shift into that state very quickly, and by the time you are walking past she may already have been watching you for a few seconds, running through the sequence internally. What looks like no warning from your perspective has often been building for a moment you did not see.

The most effective thing you can do is interrupt the hunting cycle before it reaches you, which means structured play sessions, twice a day, with a wand toy that lets her complete the full hunt sequence: stalk, chase, catch, bite. When that need is met consistently, the ambushes usually reduce significantly. It does not mean she is broken or that this is just her personality. It means she has energy that is not finding a proper outlet. If you would like to go deeper into the specifics of her day and environment, the Work With Me assessment is a good place to start because the details of her routine matter a lot here.