YOU SAID:

I'm having the best time ever currently

INTO JAPANESE

私は今までで最高の時間を過ごしています

BACK INTO ENGLISH

I have had the best time ever

INTO JAPANESE

私は今までで最高の時間を過ごしました

BACK INTO ENGLISH

I had the best time ever

INTO JAPANESE

今までで最高の時間を過ごした

BACK INTO ENGLISH

Had the best time ever

INTO JAPANESE

今までで最高の時間を過ごした

BACK INTO ENGLISH

Had the best time ever