The tree looks like its doing well where it is, the leaves are nice and green. I am in zone 5 and the last freeze date for us is May 31st. You are further south so your last feeze date would be sooner. You could try putting it out on sunny days and either bringing it in when you know the temp is going to go below freezing, or cover it with something on a cold night to protect it against a freeze.
I put my fig trees ouside yesterday, they were starting to break dormancy in our basement. Last year I kept them in the house in front of a sunny window once they had broken dormancy, I put them outside this year to try and stretch the short growing season we have here.

Hi,

Your fig tree new growths looks so lush!