Is more than 5 vowels? Is that possible?

'y' is sometimes considered a vowel because it's a rule that every word in the english language has to have at least one vowel, but words like 'my' and 'by' break that rule. Therefore it is also a rule that for words like these 'y' is considered a vowel. However, if you have a word like 'myself', only 'e' is considered the vowel for that word.