My first anxiety attack

Honestly I did'nt know what was happening so I just sat there and tried to hide it cause I thought it was nothing. I was at school in 11th grade and I had never taken the SAT test so I was very nervous before but once the test started I started breathing heavy and couldn't control it. My teacher saw me and asked if I would like a bottle of water and I said sure. The next thing I knew I felt like I was about to throw up so I asked to teacher if I could go to the bathroom and then I did and the first thing I did when I got to the bathroom and I threw up in one of the toilets and no one knew. I came back and started working on the test and then the teacher came back over and said I looked ill so she sent me home and I got home and my mom just acted like everything was normal. Then the anxiety came back. And i didn't know why because I was home and I wasn't taking the test. I started breathing heavily again. A technic I learned while I was breathing heavily was to hold my breath as long as possible then bloww it out as long as possible and then it distracted me from the anxiety it eventually ended and no one ever kneew about it.