That could definitely be the case. I guess I will just have to give him/her another month or two before I can be sure. If female, shouldn't I see its sexual organ by now?
Pack it full of food and wait lol.
You can net the fish and vent it you should definitely be able to tell that way. At that size the tube doesn't have to be showing for either sex.
If the tube is pointed and away from the body does that mean it's male or female? Sometimes after he/she eats a lot I can see a pointed organ for a few minutes.