I can see!
Sometimes an eye can just be weird for a short while and then go back to normal, but this stayed, and it's one of those things that is impossible to ignore once you know about it even though it wasn't noticeable until then.
So I went back to the eye doctor and he found that indeed my prescription for the left eye was wrong. Well, we don't know if he gave me the wrong prescription when I saw him in January to get the new frames, or if my eye changed since then. But in any case, problems with new lenses could only be fixed for free within 60 days. Since my new frames were a gift from mom & dad, they paid for the replacement lens, too. Thanks! :)
So I got the new lens put in today, and it's SO much better. I can have my sanity back now. :)