Panic Attacks Support Group
A panic attack is a period of intense fear or discomfort, typically with an abrupt onset and usually lasting no more than thirty minutes. Symptoms include trembling, shortness of breath, heart palpitations, sweating, nausea, dizziness, hyperventilation, and sensations of choking or smothering. Panic attacks can be very sudden, appear to be unprovoked, and are often...

Do you mean to tell me, that your depression went undiagnosed for "years and years"? Was your doctor only treating you for anxiety? Or was it that the anti-anxiety meds were causing depression?
Regardless... there are many treatment options, and many options within each treatment (ie, many different medications or combination thereof). There is also cognitive behavioral therapy, yoga as you mentioned, deep breathing exercises, herbal remedies, meditation, hypnotherapy and many other ways to combat your problems. My suggestion would be to begin by making yourself as strong as possible physically with proper diet and exercise, and then start doing research and sit down with your doctor to discuss a treatment program, and not just a drug choice.
Speaking of the drugs though, lots of people have to try different medications before they find the right one for them. Ask about a low to moderate dose of an anti-anxiety medication that you can take long term, as well as a prescription for Ativan that you can take if and when you get hit with a bad panic attack. Just be sure you don't rely only on the meds - get that CBT or hypnotherapy or whatever it is you choose going for you as well.
People can and do get better all the time.