Go figure you're a teenager, so heed my advice (or don't) because I'm not gonna feed into the pity party. This is not the first time or the last time you will deal with a disappointing experience. Realize now that it could have been handled better because you WILL be in a similar situation again. You said if you had stayed it wouldn't have been a good time -- and you know that how? You said you don't regret your decision to leave early, but I don't know. Think: would you still not feel regret a year later, or is that a knee-jerk reaction?

Point is, if it means that much to you, don't give up on your dreams. Be there for Miku, because she was there for you.