looks like a long variety of the winter melon. in cantonese we call the round ones dong gua and the long ones tzeet gua. the ones we grow have yellow flowers on short stems. yours are white on long stems.

Most probable Lagenaria siceraria ( bottle gourd group). Wax gourd/winter melon (Benincasa hispida)is a possibility but I think they have yellow blossoms and the fruit is shaped like a watermelon.

its been a very long time since ive grown bottle gourd, but i think they do have white flowers on longer stems. but i dont remember if they're that fuzzy tho.

give us an update once it gets bigger.