TJ has stated and I know he is correct, that the system will only hold so many users at a time.
You have people checking for others, that can not even book, so yes you are probably being shut out by those just playing around.
Hopefully this is due to it being new and people will soon realize there is no need to check what is available until you can book. It changes by the hour, even the minute, looking ahead 4 months is really ridiculous.