Typically, unstressed vowels in English transform into schwas. So confusing for English language learners when speaking and native speakers when writing. To remember what the vowel is I try to add a prefix or suffix which tends to move the stress and reveal the vowel I’m looking for.

Shingle bells- how delightful

Yes! My sympathies. This is what happens to a language that is a mishmash of multiple. I remember being a German language learner and realizing the trouble I could get in if I mixed up “ie” with “ei”. As in schießen - to shoot and scheißen - to shit

Luckily for you, it’s English and no one really cares that much. As long as we understand what you’re communicating. Unlike in French, there’s no requirement for perfection 🤣

For me it’s also a question of which syllable gets the emphasis.

I used to trip on those too. And it got me into a LOT of trouble when I first moved from the UK. Still does if I’m in west London mode. I would only attempt when I’m channeling Southern Ontario.