But they didn't say that anywhere BEFORE sending my coins.
Are you absolutely sure that they didn't mention anywhere on the site what's the minimum amount that are willing to mix? Somehow I doubt that. And by the way, nothing would have happend if you mentioned the name of the mixer.
This place being popular I just stupidly trusted them thinking since they are allowed to advertise here that they are somehow vetted by this site. But stupid me don't even know if this site itself is clean.
Scam,s are not moderated here on bitcointalk so even if you see some service havinga signature camoaign, it doesn't mean that its legit. You always have to do your own research.