Conflicted over Sexual Immorality

Both me and my girlfriend are Christians who have dabbled in sexual sin together online (as we are long distance), but we are wanting to change for the better. My conflictions are being powerless to Marry or really do anything (from what I know) to validate our relationship in god's eyes and us marrying would have to be far off as we are still in School and would be upwards of atleast 4 years for marriage to even be possible. I'm not trying to come up with an excuse to continue commiting sin before marriage but the feeling of being powerless to do anything about it for years to come is so daunting to me. I can and do love her without it but without it, it's like our relationship doesn't feel true yet, like no matter how close we get, our relationship still won't feel legitimate in god's eyes and thus our own eyes because technically we aren't married yet. Any thoughts to help these conflictions?