Low Wbc, Should I Be Concerned?

My cat is 1 year old +

I took her to the vet to get vaccine shots as recommended by the vet.

Her temperature was high (103), and they drew blood

WBC (Neutrophil) was 1.9 (normal is 2.5-6)

Went back 2 weeks later and her temperature was normal. Urine was negative. She’s negative for feline leukemia and feline HIV. after doing another blood work up her WBC was 1.3

I’m following up in 10-14 days. Any idea what this may be or should I be majorly concerned.
My cat eats, drinks, and plays normal. No changes in behavior

Was she checked for panleukopenia (parvo or distemper)? There can be a variety of reasons for a neutropenia, the most common is a heavy bacterial infection, were any other WBC values low?

Neutrophilia is an increase in the number of neutrophils in the bloodstream and is caused by inflammation. Structural changes in neutrophils may occur during severe inflammation and are referred to as toxic changes. Neutropenia is a decrease in the number of neutrophils in the bloodstream. It may occur due to the white blood cells sticking to the walls of damaged blood vessels, consumption of neutrophils (as a result of severe inflammation), destruction of neutrophils, or reduced formation in the bone marrow. Neutropenia may occur in all species during overwhelming bacterial infections. Adverse reactions to drugs may result in neutropenia or even pancytopenia (a reduction in red and white blood cells and platelets) in cats. Feline leukemia virus and panleukopenia (feline distemper) have also been associated with neutropenia.
source: White Blood Cell Disorders of Cats - Cat Owners - Merck Veterinary Manual

I would suspect some infection since the fever was also present.

My cat had a very low WBC during routine blood check with no other symptoms as well. We repeated the test 4 weeks later and it came back to normal. The only thing that changed during these weeks was that she was dewormed at the same routine visit (before we got the results) and I saw proofs of roundWorms in my other cat, so I assumed she had them too. My vet at the time didn’t think that would be the reason for neutropenia, but who knows. But she is a rather sickish kitty with FHV and chronic lower respiratory disease, it’s possible that she might just be a cat with low white blood cells (her normal WBC are also on lower end), it’s also a possibility for your cat.
If I were you, I’d keep in mind that your cat is very vulnerable right now since low white cells will not ensure the right immunity response in case this is needed. So I’d make sure the cat is free from stress, eats the best food and is kept in warm, safe space.
Did your vet has any theories on what could cause the low WBC (apart from FIv and Felv)? Actually, was total WBC low or neutrophils only?

She told me the Neutrophils were low. I am making a follow up appointment. My cat has no change in behavior or diet. Im hoping this is just normal for her. However whenever I take my car she gets SUPER STRESSED. Other than that she roams the house and is great around my wife and I. So I'm not too sure