The problem with these symbols is that every one of them means an abstract thing: a phoneme. We don't utter phonemes--they exist only in our minds. We realize phonemes in various ways depending on our accents. We call those realizations allophones and none of them is the only correct one.
There is nothing strange about your problem. The problems with consonants are usually the first a European learner of English overcomes, which has two main causes in my opinion. First, the consonants are mostly the same in all Indoeuropean laguages. There are differences, but they're not numerous. Second, the differences between English consonantal phonemes are usually easier to recognize than the differences between vowels. Vowels form a continuum of sounds and the boundaries of different phonemes often intersect.
I was very surprised recently to hear a sample of the /ɨ/ sound, which is said to be one of the Polish phonemes. I knew of course which Polish sound it was, but the sample wasn't it. It was a sound no Pole would ever produce speaking Polish.
It's virtually impossible to give symbols to all possible (or at least all recognizable) vowels, because there are simply too many of them.
Student or Learner