I'm so furious.

I don't whether I am over reacting or not but I'm so irritated right now. Today while cleaning the house I came across a bag that had two towels in it, one being mine. Those towels were used to dry my dog off! While I don't mind drying them with our towels I don't think it's right that mine was used to dry the dog off. Who does that without asking who's towel it is? Yes, we have more towels but my point is why not ask me first? I kept looking for my towel the entire time until I gave up and said fuck it I'll get a new one. Anyway, my frustration comes when they don't asks for stuff and think it's ok to just grab and use it. My fiancés daughter who's 15 years old has a tendency of stealing my clothes or using my stuff without permission like she runs the house. And my fiancé has nothing about it but the other day his daughter wore her litter sisters shirt which barely fit and the other sister threw a fit and said she always using her clothes without asking first and then stretches it as well. My fiancé went off on his 15 year old and I'm thinking to myself that she's indeed stolen my clothes, underwear, bras etc and has wore it without asking me or letting me know. When I told my fiancé he didn't say anything and just told her to respect my stuff. That was all. I'm just over it.