HI Gabriel,
This is a lovely question, and I chuckled when you started to goof around with the tones, it sounds so funny when I sound them out mentally!
So, why wo3 hen2 hao3, and must be in that order. It’s because of de facto use, and you sometimes do hear a native speaker saying wo2hen2hao3 (even though in print, the tone change is never written out, it’s reflected in speaking only). There are rules which are complicated to explain for beginners, and so we want to keep it simple for you for now.
My own explanation to this 3-3-3 sequence is as follows. In Chinese, you often can drop the subject, i.e the first word and the sentence can still make perfect sense. For example, wo-hen-hao. If you reply simply 很好，it still makes sense to the person you are replying to. And here, you simply use the tone-change rule, i.e. 3-3 becomes 2-3. So you say, hen(2) hao(3). And when it comes to first word 我/你， you can say it with wo(/你2), wo/你(3), or even wo/你(4).
So I hope you can try to use this simple rule and come up with more examples yourself. It should be easy to pronounce (for you) and sound natural to listener. There are some very obvious exceptions but I am guessing that you won’t encounter those words and phrases until later and so for now, it’s better not to confuse you with them.
Here are some examples:
我想你 and read 3-2-3.
狗很好 and read 3-2-3
果(子）很苦 and read 3-2-3
Can you think of some samples too? And please tell me if my “rule” helps?
