My mom invades my privacy?

So long story short, my mum was booking a train ticket and needed my email address and I wanted to log into my emails myself so that I could click the confirmation but after she pressurised me into giving her my password which I felt uncomfortable doing because even though its for something as dull as my email, its my emails and my password (im 17) and like I don't want everyone knowing my password. anyway, my password for fb and instagram is the Same and ive now had to change them because I KNOW she will go and look through my stuff. I have nothing to hide- I just want to be able to have my privacy without her looking through my facebook messages or what have you. is this bad?