Hi Joshua,
In order to understand and learn Tagalog, one thing you have to do first is to stop finding English grammar comparisons because it will confuse you more. Take the language as it is and don't find "grammatical equivalents". There are many concepts in the Tagalog grammar that don't exist in English.
Also, using the wrong pronoun can change the entire meaning totally and still be grammatically correct. So using the correct pronoun relative to the verb conjugation is very critical.
Examples:
Ako = I, ko = mine/I, Kinain = completed for of Kain(eat), Kumain = completed form of Kain(eat), ang/ng=markers, isda = fish
Kumain AKO ng isda. I ate fish, emphasis on the doer/what I did. Answers the question "What did you do for lunch?"
Kinain KO ang isda = I ate the fish, emphasis on what was done to the fish. Answers the question "What did you do to the fish?"
Now, take a look at this sentence: kINain AKO ng isda = the fish ate me. See how the meaning changed when AKO replaced KO in the -in- conjugation?
For "possesive ko": Isda KO iyan = That is MY fish. Iyan = that.
Let's change ko/ako to mo/ka
K-um-ain KA ng isda. You ate fish
K-in-ain MO ang isda. You ate the fish
K-in-ain KA ng isda. The fish ate you
Isda MO iyan. That is your fish.
Also, "Ginagawa ka" and "Ginagawa mo" have different meanings. Ginagawa mo = what you are doing. Ginagawa ka = you are being made. As in "Ginawa ka na bola". You were made into a ball.
It gets more complicated with other conjugations. "Ginawhan KA ng bola". A ball was made for you