Hey Shelby,
I started RP too with the desire to put on some muscle. I've always been a thin and a relatively hard gainer. After I finally got my diet sorted out, I am as trim and stong as I've ever been.
Muscle building requires protein, fat, and nutrients (among other factors - get to that later). You simply cannot get enough of all of these while on a vegan or vegitarian diet to satisfy long lasting growth. The best thing you can do is eat fatty red meat, and lots of it. You will get plenty of protein, fat, B vitamins (which are difficult to get on vegan diet), and allow your body to absorb fat soluable vitamins (A,D,E,K). Having been a former vegan, you should definitely consider eating a few ounces of liver at least once a week as well. It contains massive amounts of A and B vitamins, and it's very likely that your own stores of these vitamins are depleted. The eggs you are eating can be a good supplementation, but shouldn't be the the mainstay of your animal food intake. Also, I'd guess you probably eat plenty of nuts. A small handful once or twice a day is okay, but any more than that is really not helping you much, better to get your calories from animal sources, as they are generally easier to digest and rich in nutrients.
If you want to eat plenty of red meat and fat without putting on excess amts of fat, you will need to limit your carbs. Of course, paleo eating means no grains, rice, pasta, oats, bread, potatoes, etc, so that makes it a bit simpler right away. I would stick mostly to berries, and 1 piece of fruit a day. You can also eat your red meat with some non-starchy fruit/veg like bell pepper, avocado, onions, tomatoes, etc, just don't go overboard. Ultimately, the goal is to work your carbs down to 30-60g per day, so that your body switches from carb burning to fat burning metabolism - known as ketosis. This can take a few days to a few weeks, and it's probably best to move there gradually. Remember though, if you are not eating plenty of fat on a carb restricting diet you will lose even more weight. If your interested to learn the basics of insulin response, and why excess carbs are detrimental to health, check out
http://www.biblelife.org/rosedale.htm The begininning is a bit dry, but after the first couple sections it really starts to explain whats going on metabolically.
Last thing - exercise. It looks like in your avatar you are running a marathon, or some type of long distance race? I can tell you, you will never bulk up or get to a healthy weight doing long distance, endurance type sports. They automatically put your body into a prolonged catabolic state which consumes your tissues to provide energy. If you really want to bulk up and put the right type of weight on, you need intensity. Short bursts of strength over a 20-60 min period, followed by a good meal. What this means is you can either do very fast sudden movements with lighter weights (sprints for example) or heavy weights with slower controlled movements.
www.crossfit.org has TONS of great exercises for overall health without much weight. Also, it looks like you're a pretty thin girl already, it could take some months, even a couple years maybe, depending on just how much muscle you are trying to gain. Then again, perhaps a radical shift to an optimal diet will give you a few extra pounds of lean mass in just a few weeks.
Keep us updated on what you decide to do and how you're progressing.
-Jason