Most of your postings are in the Male Fragrance Discussion forum, so I'm assuming your "Undisclosed" gender actually secretly involves sporting a kickstand. So I'm guessing you are talking about L'Instant de Guerlain Pour Homme
. The first point is that it is a very good fragrance, but you can already surmise this from the abundance of positive reviews here on BN. It's not like it's something that will make you smell like you've been wrestling unwashed goats.
If you're 19 years old, I'm guessing your mother and sister are reacting more to the fact that you are wearing a fragrance at all, and it probably has nothing to do with L'Instant
itself. Your mother probably figures this is precursor behavior to you either moving out of the house or getting someone pregnant. If your sister is like my sister, she never liked you much in the first place.
If neither of these is the case, you can simply write them both off as having embarrassingly bad taste.
Bathe in it, and wear a beanie hat with a propeller to create artificial sillage. (The hat will also reduce the chances of that pregnancy your mother fears so much.)