hmm... I'm probably not the best to advise, as I probably started around 13 years old, and since then have not been able to keep my hands out of my panties for too long ..
but anyways -
I would say that, yes, I think a sexually active person should be able to masturbate.
you should care, and you should work on it.
perhaps instead of just going right for 'it' ...
start slow ... get used to touching your body, in general.
then, when you feel comfortable with it, and horny or wanting to be, touch yourself a bit more sensually .... run your hands around your hips, up the side of your waist ... fondle your breasts a bit ... and your ass ...
do that enough and you really should feel like sticking your hand between your legs.
trust me