I would ask a psychiatrist. The problem with using this med for anything other than its intended purpose, which is for heart problems, is that if you stop and start as you say you can potentially adversely effect your heart. While this class of drug is used for a couple types of anxiety, there are many who don't like it for that because it does affect the way the heart works and if your heart is working fine, you don't want that effect. That's why I'd fully discuss it with both a heart specialist and a psychiatrist and do some homework of your own to see if it's right for you. The fact you're not having side effects and it appears to be working is a strong argument to find a way to keep taking it, but you do want to do that safely. As with many meds used for mental illness, the real problem can come when the time comes that you need or want to stop taking them, and one should be prepared for that beforehand. Peace.
This medication can be prescribed PRN or as needed for anxiety situations. For anxiety situations like performance anxiety or social anxiety, the dose is usually 10 to 80mg. So, you don't sound to be taking more than you should and if it is prescribed prn, there will be times that you don't take it which is expected. Does it help you?