Welcome, Princess_K!
Whether you are questioning, exploring, transitioning, or something else entirely, you've absolutely come to the right place. I experimented with crossdressing on and off in some form from the time that I was around 12 years old or so. The problem was, even when I still struggled in denial and repression, there didn't ever seem to be anything 'cross' about it. Similarly to you, I started out mostly with my sister's clothes and never thought much of it growing up other than I knew I liked it and that perhaps one day I would like to pursue it further. As far as fighting the urge? I guess you could say all of my life, up until the end of November, 2016. My earliest memories pertaining to being transgender go back to childhood, probably to as early as 5 or 6 years old. Ironically, the earliest memories of having that curiosity/desire didn't start cropping up until after two little girls who were my age and and lived nextdoor to me, that i used to play with all the time, moved away. I remember little things like being curious to know what being a girl was like, wishing I could wake up as a girl, or that I had the ability to switch back and forth. Even then, all of those thoughts were accompanied with an extremely troubled feeling that persisted until shortly before coming out of denial and accepting myself in the last few months.