Going out on a limb a bit here, but I feel like "I" in a first person (non-dialog) narrative is redundant in a way. It's already first person, so "I" doesn't really add anything of value. I wouldn't say it's inherently bad, but an alternative is almost always better.
In real life we only really think of ourselves in terms of "I" when we are actively thinking about our whole self ("I think I will go the store"). Most of the time, however, our thoughts are more specific than that. When writing, for example, you don't think to yourself "I am currently writing", you simply see the page, the pen and your hand and they are doing the writing. Sure, your brain is telling your hand what to do, but that's not what you are thinking about. From your own perspective, you are not the actor; the objects, people and events around you are.
So, to actually answer your question: "Am I using 'I' too much?"
Without seeing more than the sentence you gave, I can still say, with absolute certainty: yes and no...probably. Sometimes the story does actually focus on the characters actions (more like over the shoulder 3rd person in a way) and frequent use of "I" helps reinforce that. Sometimes there is just no other reasonable way to write the sentence and you have to make it work.
I think the two biggest things to keep in mind are:
1) Using "I" often reduces immersion (for reasons stated above)
2) There is often a better, more desciptive and immersive way to rewrite it without using "I"
For example, we could say:
"I started thinking..." >>> "My thoughts began to drift..."
"I nervously wrote..." >>> "The pen trembled in my hand..."
"I couldn't focus..." >>> "My mind refused to stay on track..."
The example in @Amadeus-Reinstate-Monica 's answer illustrates this perfectly