My horoscope is very special. According to the lunar calendar, I was Sagittarius last year, but last year I became Capricorn. So, am I Sagittarius or not? ...

I suggest you calculate according to the Gregorian calendar. Because the constellation was invented by foreigners, and foreigners look at the Gregorian calendar, so you'd better use the Gregorian calendar to calculate. I think you should be Sagittarius. Check Sagittarius and Capricorn on the constellation website to see which constellation your birthday is in.