You don't need a beta, if you use Microsoft Office, you can listen to the story. That's how I proof my stories, and it's reduced my mistakes considerably. Also, might I suggest, adding a chapater where Ron actually grows a pair and takes Kim, where he finally get's over his insecurities about Kim leaving him, and becomes more confident with her. He doesn't have to be a domineering asshole, but a little swagger is not a bad thing, Kim may grow tired of being the one to start things off, she may love that this is the one aspect of her life, where she doesn't have to be in charge.
But for the most part; this is a pretty good story that you put here, very touching and romantic. :)
You can also go to Fanfiction.net and look up samuel adams 17 and my profile will pop up with a story, "When The Unthinkable Happens" that is where you can get ideas for you story. Hope this helps!