Why Is My Mom Mad That I Want My Own Account?

When I was in high school I had an high school bank account that was linked to my mothers bank account because I was a minor. When I started college and turned 18 I got a college bank account so our accounts became unlinked. I am now in my second year of college and I made a big purchase on clothes with some money I got back from school, when I got home before my mom even saw my bags she started yelling at me saying, "I thought you were saving your money to shop for the holidays," after a long argument I found out my mom linked our accounts back together and has been watching my spending. What is even worse is that she told me that she linked them a few months ago but when I went to the bank to change it I found out that the accounts has been linked back together since the day after we unlinked them.

When my mom found out I unlinked the accounts she was pissed and now every time she speaks to me she has an attitude. My Brother told me I did the right thing and my Dad told me that I shouldn't have done it but I feel that I did the right thing. I'm 19 and although I live at home and my parents pay my tuition I have my own job and I buy 100 dollars worth of food each month.

I just want some more opinions, Does my mom have the right to be mad at me? Why or why not?