i didn't know i would be able to (if i could) sex the plant when it's so young. correct me if i'm wrong but i think i see a girl coming. comments / corrections greatly appreciated.
still too young. all mj plants female and male have the green "hairs" at the nodes. what you are looking for are small white hairs called pistils coming from the pre-flowers.
Unless it's auto flowering, which it doesn't look like, it's pretty unlikely to express sex yet. You could sex it if you put it into 12/12. Some poeple do it to weed out the males before LSTor SCROG. You can put it back into veg once it expresses sex by changing the photoperiod back to 18/6.