20 years says your problem is a chronic one, and not just something that crops up when you are experiencing a lot of stress or something.
OK. The REAL problem is that docs don't really have the time and/or the complete understanding of how this works, which means that you have to become more actively involved in pursuing your own mental health.
Everyone's brain chemistry is different and responds differently to different SSRIs. When my life was crappy I was panicking a lot, went on 20mg and after a while it worked but I felt a little zombified. I had the sexual side effects, which was actually OK because my wife then was a frigid bitch who didn't appear to like me.
But finally it occurred to me to go down to 15mg. No doctor told me to do that, I just figured I should give that a try. Voila, all the side effects went away and I still had no panic.
In fact, not only did the side-effects go away but I was actually multi-orgasmic for about a month. What a waste for that to happen while I was still married
Still I didn't get much done that month
After a while of working well at 15, I went to 10mg, and three months later, some panic resumed. Back to 15mg and that was the right level for me.
These days I have a better life, and have reduced to 10mg and it seems like the right level in many ways.
The next question is how far you are willing to go to address it, and how much money you are willing to spend. Along these lines, a doc prescribing you Paxil CR is just reacting to your worry about missing a dose. Paxil CR was invented because the patent protection on regular old Paxil has expired. That means you can get Paroxetine instead, the generic, and in fact Pennsylvania pharmacies will do that exchange by default. They won't exchange Paxil CR. The half-life of Paxil/Paroxetine in your body is 23 hours, and you know, you could do the math on that to figure out what missing a dosage means. The psychological "half-life" is much longer, which is why it takes two months for the full dosage to affect panic.
Furthermore, I "game" the system by buying larger tabs and breaking it up into the size I need. I have a pill guillotine. I have my doc's confidence as a smart person who is actively involved in my own health.
One last note, I am utterly frank about this sort of thing, even though it may open me up to people thinking differently about me and criticizing me and such. It's because I feel it's important to be frank and honest about this. Because almost nobody is frank and honest about these things, and that prevents us from understanding them.