Easy! "Feel fun" isn't English - it sounds as if someone has been trying to stretch the meaning of "have fun" (which means "enjoy").
Now I come to think of it, "feel amused" sounds a bit odd; you either are amused or you're not.
These are all possibilities:
It was good fun
I had a good time
I enjoyed myself
Thank you for your reply and giving me some examples. Since I've read these expressions in some sentences of internet, I thought I could use them...