Answer: "I" is the subject of the sentence.
Explanation: A subject is one of the two main parts of a sentence. It usually appears before the predicate (the second main part of a sentence) to show what the sentence is about, or who or what performs the action in the sentence. In this the subject is usually in close proximity to the action word (verb). "I" as the subject is next to "have" which is the verb (action word). The subject is usually a noun or pronoun and all modifiers that go along with it.