Go into the console in the wallet and type getstakesplitthreshold. You can change that value with setstakesplitthreshold . My understanding is, that would have to be smaller then 8994 to split your output. I'm not sure if or what the default is.
This feature is nice to automagically prevent your blocks from becoming to large.
I executed this command and came out this value:

{
"split stake threshold set to " : 2000
}
Do I need to change something? Thank you in advance.
Thats the reason your output split. If you have a target block size you can use that set command to set it to the target. The blocks won't split until the resulting blocks are at your target. Basically the blocks can grow to 2 X's the threshold.
