Hello!
I know exactly how you feel. I've been there. Yes, you will see happier times again. Something must have triggered these panic attacks. Did something happen weeks ago to bring all of this on? Remember, the cure to panic attacks is getting through them without adding second fear. Some people may never have another panic attack and others are prone to them.
Don't fret about the heart beats. I've been dealing with those since November. It took many months for me to get convinced that my heart was fine and that these strange beats or fast beats wouldn't harm my heart. Once you know all of these symptoms are harmless, they will subside. They have for me. I remind myself that they are harmless. I just let them happen without fearing them.
I agree with Kitt that increasing your anti-depressant sounds better than introducing another new med. But, I'm not a professional and the doctors know best most of the time. It's probably a personal decision and something you should bring up with your psych. Your body is getting used to the anti-depressant. It will take time and then you'll feel so much better.
Get rid of negative thoughts. Make sure you're eating properly, no caffeine and getting some sort of exercise. Happier times are ahead! Don't give up and stay positive!!