Hello Jakai,
A high WBC is the primary indicator for Leukemia. But I was confused on the meaning of high. Some people are really concerned at 13K. While this is high it does not mean Leukemia.
I was diagnosed at 280K... So you can see that there is a big jump from 13 to 280!.
I also had a enlarged spleen that REALLLLY HURT when I would breath. The fact yours is removed might be a reason you WBC is high as it is used to remove WBC as well as sweat them out.
So, try to stay calm even if this is a difficult time. I will tell you that the treatments for Leukemia have come a VERY long way. Depending on the type of Leukemia you will get a specific course of treatment. I have CML and I take 4 pills a day and that is about it.
To figure out the type you will do a BMB (bone marrow biopsy) so that they can see the DNA strands to tell the gene pairs. My advice to you is if you should need a BMB ask them to put you under and not bedside. My first BMB was done bedside and I almost broke the bed pulling on the frame.

They might not like that you ask for this but you are the patient and no need for you to have ANY pain for the proceedure.
All the best
Keith