There could be more blockages that are too small to stent. In my case, some of my angina is actually spasms. I do have an artery that is 50% - 60% blocked and I will have to have bypass with that one. I want to hold off on that as long as I can. Are you taking a nitrate? There are some good ones. Isosorbide is one that is long lasting. I take that, but also keep NitroQuick with me to use.
Hi. I had the stent deal when I was 42 so I can relate to your concerns. Before I go on, remember that every person is a unique case. Unfortunately in mine, the stent wasn't enough and I had to have a single bypass. I was very freaked about it (and everyone in the hospital was asking why I was in there at my age). In my case I had a clot that no one could explain since my heart was healthy in every other way.
I am sure you know that you have to go to your doctor and tell him about the continuing pain. It doesn't necessarily mean you need a bypass... but you do need to find out.
By the way, after my bypass everything was shiny. I had no more problems and it has been 12 years now.
God luck and be strong.