Yes she can catch mono from you. You have been contagious for 5-7 weeks. The only way she won't get it is if she's had it before. She could have had it as a child, you can get mono anytime and by the time your a teen, there is a 50% chance you've already had it.
You will not be contagious after a month or two. You don't have mono for the rest of your life, you have the antibodies in you that prevent you from ever having mono again! So once you have mono, you can't get it again.
So, if you've been kissing her all along, it's not going to make any difference if you kiss her now.