Do you consider lesbian sex to be sex?

So, if you had your first sexual experience with a female and you are also female, would you tell people that this was when you lost your virginity?
I say yes, because I exclusively slept with girls for 8 years and am now just recently dating a guy and had sex with him, which was the first time I'd slept with a guy. Now, I tell people I lost my virginty at 14, because that's when I first had sex with a girl... But my sister argued with me that it's not right. (Which I don't agree with and its my life so F you,) but I just wanted to hear other people's opinions on the matter. :)