Sadly, I think the only thing you can really do is hope that someone declines an offer at the school you're waitlisted at-- though this year it seems like perhaps programs are just waiting it out in hopes of enough funding to open up for an additional spot? In which case, try your hardest to figure out where you are on the waitlist. In my experience, being in contact with the DGS can't really hurt, but it doesn't really help either-- I think they all understand how stressful the situation is. I was waitlisted at U of Oregon Ph.D in English Lit program last year while my partner had an offer from them. We visited the program and were treated so well by everyone there. Elizabeth Bohls, the DGS there, was especially sensitive to my quite tender psyche, and visiting made both me and my partner feel so good about the program. I was number one going into the last month of the season, but, alas, only got in once my partner declined. Liz Bohls knew all of this and while I am currently not in a program, I got let down in the nicest and most conscientious way, and that, as far as I'm concerned, was worth the trouble I took to pester.
My partner decided to take the offer from UC Davis, where, incidentally, I'm number one on the waitlist this year (I think I might actually BE the entire waitlist?), where it seems they've limited their offers. At this point I have, as they say, put all my eggs in one basket and withdrawn my other applications. I really want to go to school, but I also really, really want to live with my wife. This whole thing (constantly twisted stomach, loss of appetite, sense of doom) feels awfully familiar.
I'd think that you might comfort yourself a bit if you're waitlisted at some good schools-- the better the school, the better the chances are of the accepted having a number of other offers-- and the better you should feel about your application-- after all, the worst part of all of this is feeling like you're no good, which is probably never actually the case. If you do talk to the DGS, you should be able to get a good feel for how likely it is that you get in, but they also have to be rather non-committal per their responsibilities.
I suspect that writing all of this down has helped me feel better as opposed to you, so I apologize. Hopefully there is some useful sense of camaraderie; I offer you my very best thoughts.