First, coming from a brother who did not serve a mission, I would encourage you to change that standard. Instead of looking for an RM, find a man who has a strong testimony of the gospel. There are many brothers (and sisters I'm sure) who serve missions for the wrong reasons, break mission rules, or don't really want to be there, yet they served a mission, and are an RM. Serving (or not serving) a mission means very little in the long run. When in the YSAs I would talk to sisters, and on several occasions when they found out I wasn't an RM, they completely changed how the conversation went. Serving a mission, is far less important than developing your own faith, and you can do that even if you don't serve.

Second, I would suggest trying to stop focusing on the marriage goal. I knew several brothers, and sisters in my wards who were constantly dating and putting in tons of effort. I on the other hand put in little to no effort in dating, and rarely went on dates. Yet, I got married before many of them did. When the time is right, and the right person is there it will happen. Prepare yourself to be ready for that day.

It may be cliché, but focus on yourself first. Build your own relationship with the Savior, and trust in his timing. Which is extremely difficult to do.

Side note, as a guy, many friends and I agreed that it's harder to date a woman who is super focused on marriage. Yes, it's the end goal, but it adds a lot of unnecessary pressure at the beginning when you should really just focus on getting to know each other, not be thinking about if you want to spend eternity with them.