The bulimia angle is interesting. Maura was a big track and field runner, if I remember correctly, so it's possible she was quite concerned about her weight.
I am absolutely convinced she had a very serious drinking problem, if she wasn't already an outright alcoholic. Didn't she wreck her father's car after being at a party? Then all the alcohol she bought before taking the trip that was found in her car after the second accident. She'd been drinking while driving, too. I think she was moderately drunk when the accident occurred and, remembering the earlier accident, became quite concerned about the arrival of the police. They would've smelled the alcohol and found the booze in the car, and Maura quite likely would've went to jail on a DUI charge. Family and friends would learn about her drinking problem, and that would shatter the image Maura wanted to project about herself. She took off on foot to get away from the accident. Throw in a possible head injury from the accident coupled with drinking and I think it highly likely she got confused and wandered off into the woods. She got lost and died from exposure. It's possible someone might stumble over her bones out there some day.
There's the issue of the phone call to the boyfriend sometime later, but I've never seen absolute confirmation that the call came from Maura.
I think Maura may have had an underlying problem with anxiety, which could have lead to problems such as an eating disorder or an alcohol problem. If she was shy as a child, I can see anxiety overcoming her at times as an adult, especially when she often tried her best at everything she took on. She was quite the accomplshed young lady, but sometimes the pressure and stress can lead to crutches if she suffered from anxiety. I have a problem with anxiety and I finally recognized it a few years ago. It helps to recognize it, so you can find healthy ways to deal with it.
This is all speculation and my opinion.