M'ath, zhey kalessi laowen, and welcome to the Tongues of Ice and Fire forums! I hope you find this to be a useful resource in your quest to learn Dothraki.
I see you are involved in a number of other fandom communities. I am very heavily involved in the Avatar community as well and specifically in LearnNavi, who sponsors and hosts the Tongues of Ice and Fire site. They are worth a visit as well.
Things are kind of quiet here right now, with most of the activity being in the Valyrian wiki. There has been very little new development in Dothraki, as David Peterson has been occupied by other projects. There should be a flurry of activity here when his new book on learning Dothraki hits the bookstores in early October.
The vocabulary on the Dothraki wiki is authorative for the langage, and is kept quite up to date. The dictionary, while not officially authorative, is never more than a few words behind, and is connected to a database used by various language learning tools. The wiki contains pretty much all the grammar info which we are aware of, which is actually quite a lot. It will be updated with any new grammar we learn from the book, although David has been pretty good in helping us keep it accurate.
Feel free to ask questions here. Although my Dothraki has grown a little rusty due to me needing to really focus on Na'vi right now, there is another user here, Qvaak, who probably knows more about the language than any person besides David Peterson. His detailed posts are very much worth reading.
Good luck, and enjoy your Dothraki adventure!