Ah, that’s called being “Nice”.
It means you don’t react when you’re treated a little bit badly, so people think you don’t mind, so they treat you a little bit worse, and worse, etc.
Then you get so fed up you have to put your foot down, stop putting up with it, and they think you’ve changed / gone all hormonal on them.
Sound familiar?
And yes, being a bit more assertive is the answer.
Anyway, Aleigh, I’d say you are quite good at making new friends as well, so you’ll be fine.