Does my blood oxygen level make a difference in how severe my pulmonary fibrosis is?

Yes... Pulmonary fibrosis causes scarring in the lungs. The more severe it is, the lower the oxygen level will be over time. It takes quite a bit of scarring to actually lower your oxygen level and your oxygen level should be monitored over time with pulse ox and/or abg analysis.
Yes. As pulmonary fibrosis becomes more severe, the ability for oxygen to get to the blood becomes more and more impared. This results in lower oxygen levels.
Yes. The severity of your pulmonary fibrosis affects your blood oxygen levels. Areas that are fibrosed do not absorb as much oxygen as healthy lung tissue.