The symbol ə is the most deceptive of all. At first it is not a unique sound, it can sound like many others.

or the "ɪ"

But the most important thing is that it is not pronounced like the other vowels. It is pronounced reduced and sometimes it is almost not pronounced, it is only the sound that escapes when passing from one consonant to another.
So at all costs you should avoid putting one of your vowels in its place. IT IS NOT NONE OF YOUR SOUNDS. And together with the other sounds pronounced with "Primary stress" and "Secondary stress" are those that create the information system with which they communicate.
The information is in the variations of intensity and duration of the sounds.
So forget about saying how you think is right.
To speak as a native speaker of the English language, you will have to reduce function words, reduce the unaccented syllables of the content words, put the necessary "stress" in the syllables with "Primary" and "Secondary" stress, use contractions naturally, without considering them deficient or current.

And to achieve it, concentrate on a single dialect.