Hi! You wrote this really well! I just have some suggestions that should make your message more clear. Since you had more than one class that day, you should say “I had class from morning to evening” or “I had classes from….” Both “I had class....” and “I had classes....” work, but I think it sounds more natural to say “I had class from [point in time] to [point in time].” Also, I think using “regret” in this situation sounds weird. “I was disappointed” might be closer to the feeling you felt. When you do use “regret,” though, usually we use it as a transitive verb, as in “I regretted not working harder” (as opposed to “I was regret”—that sounds unnatural). よくできましたね！