Congratulations on growing a tree from a lemon seed! Keeping it alive in the winter is also a reason to be proud. Unfortunately the seed from a grocery store lemon may not be able to produce the same lemon as you harvested the seed from as most commercial lemons are hybrids so the seed does not breed true. The Meyer Lemon is the variety I recommend for indoor and outdoor use as a potted plant in cold winter climates like yours. You can find this variety as nurseries often sold as a houseplant.  You should still continue to pamper your seed grown lemon tree as it may surprise you with fruit after a decade or more. Plenty of sun and heat is what this citrus fruit needs to flower and make fruit. Keep growing, Marianne Binetti