Sudden loss of hope which causes panic?

Hi so I was diagnosed with depression a year ago and had psychotherapy for a few months but then gave up with it. Now I'm starting to have weird attacks that happen at different times of the day. Sometimes I'll be happy laughing away and then all of a sudden I lose all hope in my life and start panicking to the point that I actually think of killing myself to stop the panic (but knowing I won't which intensifies the panic). It's not a full blown can't breath panic though, it's more of a struggling panic as if I'm trapped and trying to get out of my life or something like that?

I'm not sure what it is so I'd be very greatful if someone could inform me about what I am experiencing everyday because it's really getting to me.

Thank you