+1 Shanai Marriage Honey (this is an all-time favorite of mine & is worth mentioning even though it's a jdrama rather than a cdrama)
+1 Love Me, Love My Voice
+1 Amidst a Snowstorm of Love
I'd also add the following:
Forever and Ever (helps if you've seen One and Only, but that definitively DOESNT fit your vibes)
Hidden Love (this one has high school elements in the flashbacks, but it isn't really a high school drama)
Hi Venus
Marry Me!
Love O2O
The Oath of Love
There are other good ones if you're willing to watch more than 30 episodes