How to overcome anxiety and panic attacks?

Hi doctor,

I do not know what is happening to me but I overthink a lot right now. My life is perfect but I live in the past regretting mistakes and feeling guilty and depressed. I want to study a lot but these things always bother especially at the time of the exam. I always think too negatively because of the past and then about the future and I imagine myself in the worst conditions. All these things make me extremely anxious and have panic attacks which feel like something is bothering me in my chest like a weird pain. I also feel emotional about myself then I cry from my heart. This all happens when I am alone at home and increases at night. I also have a phobia about some places in my home town like my school and also about some people's bad past friends. I never want to see them in my life. I feel insecure with friends and sometimes feel like all are judging me and overthink about them. Sometimes I also feel happy when I think it is in the past and this all is just temporary thoughts. I think I am over-sensitive. I want to stop this as soon as possible and just want mental peace and concentration power. I get more anxious when I correlate this problem with my study as I am very worried about it and just want to study peacefully. I want to feel confident about my career and I want to win this fight. But I need a solution to this problem. Please help me. I am just 19 years old. I do not follow sleep hygiene and cycle. I am also staying at home all day and eating outside food. I have less communication and socializing with others. I do not do any physical fitness or exercise as I feel too lazy.