When to use “I” or “I am”

I've been having some texting with someone else. None people are English native speakers, however we are both pretty advanced. She thinks I'm advanced than her, although I believe I just have more experience; however about knowledge and language dominion, we are pretty comparable.
I have some doubts, since in a minute she composed: “I'm really envy how good you understand English, but I pretty sure that it's all the outcome of hard work”.
I understand properly of this sentence is: “I truly envy how good you are in English, however I'm pretty sure it's all the result of effort”.
“How great you understand English” sounds ideal to me. My doubts are about:
- “I'm actually covet” -> “I really envy” and
- “I pretty sure” -> “I'm pretty sure”.
By instinct, I make certain the variations at the ideal side are the appropriate ones, however I don't know how to describe it, and I have not found anything about the differences between utilizing “I [verb] and “I am [adjective/ adverb].
In fact, I have actually discovered that “I'm” is used before a verb, to be detailed and to announce your place: “I am walking to the shop”, “I am a medical professional”, “I am at the shop”. However also, it's utilized before an adjective or adverb in easy present: “I make sure”, “I am hungry”.
In contrast, “I” is used in easy past, future and easy present, frequently followed by “to be”: “I have to go to the store”, “I prepare hamburgers”, “I envy your abilities”.
I've been browsing all over the right uses of “I” and “I am”, and I haven't fount anything regarding this doubts.
Why is my idea right, or if it's right at all? Are both variations right?