Leeneia:
Y is not always pronounced 'uh'.
Rather than word it myself I thought I'd just lift the description from Wiki:
"The rules governing the letter Y are some of the most confusing in Welsh. Normally it's pronounced like the u in cut, but in the last syllable of a word it most commonly represents the sound of the ee in beet. Note; This includes words with only one syllable, such as llyn (hlin)."

This may be further complicated by the need to look at the origins of complex words. So, in Pontypridd they have Ynysangharad Park. As that is a compound name the first part is 'ynys' meaning 'island' and that is pronounced 'unnis' even though the second 'y' is not in the last syllable of the name itself, Ynysangharad retains that pronunciation.
'Pontypridd' itself causes problems. Most say 'Pontuhpreeth' but shorten it to 'Ponty' (Pontee).

Confusing? or what?