The map I've been working on is... somewhat detailed. When I compile it, the BSP is around 14.5 megs, and its only about 3/4 done ( I still have to copy the main building to the other side). The only other map I've seen that is this size is DasTower. Is this a bad thing/way to large a file to be acceptable?

It's odd, because a lot of maps I've seen are a bit more visually detailed, but much smaller. What can I do to fix this?

Large BSP's shouldn't be a problem as along as the map runs fluently.
The new slimepit map weighs around 15 MB as well, due to a more detailed lightmapscale (sharper shadows) and still runs smooth enough.
So don't bother if your BSP gets larger as long as it's smooth ingame.