It sounds like you have a bit more!

True! I think we have some extra sounds like "g" which is a fricative that English doesn't have, and "double vowel" sounds like -eu- in words like "deur", but the problem comes from our spelling and pronunciation of words. The same letter (like i or e) can sound very different. There is a similar problem in English I think. I will post a video below which is very interesting:

So if I've understood correctly, when you combine certain two letters, that makes a whole new sound? And of course different letters, different combinations, right?

Yes, if I understand you correctly. To use the "watter" and "water" example again. Theoretically, it would have been more efficient to make a linguistic system where "w-a-ter" was a long a and "w-aa-ter" was a long sound. Or even better, like in other languages, get two letters! I.e. make a more phonetic alphabet.

really hard because there are no alphabet for that

Exactly! I think this is related to the paragraph above. Afrikaans has a very "poor" alphabet, that is, we have more sounds than letters.

it's also sad when there are certain languages that vanish forever

Exactly! I think I brought this up in the other comment. Languages are dying. And if you follow the rather radical thesis that language in some manner creates your reality, it is even sadder to think about it.