Ok, I feel like I owe DoDMERB an apology. Last post I mentioned I sent them an e-mail and that I didn´t expect a useful asnwer. I got the answer 1 1/2 days later. A brief but excellent:
Your username is Ambermutt.
Wow, thank you.
Update: Drat. I tried to sign in again, and apparently the problem is not with the username (which is exactly what I thought it was), it´s with the password. I´m going to feel like an idiot sending another e-mail saying "Hi, me again. I messed up before, the problem is with the password. Could you send that, too?". How incredibly irresponsible, but damn it, I´m sure of the password!