[taeric]

Ah, I think I see. You actually pronounce the "y" in those words? I'm not familiar with any dialects where that is common. I could see it, though. In general, I would expect the pronunciation for all of those is the same. They are all words with the root "day".

Copying from Merriam-Webster for them:

  Today: tə-ˈdā  
  Friday: frī-dā
  Yesterday:  ˈye-stər-dā

The page for Friday does have "-dē" listed, as well. Which maybe is what you are referencing?

Regardless, fun reading. And please don't take this as a criticism of your pronunciation!

[gus_massa]

From https://dictionary.cambridge.org/pronunciation/english/today it looks like it's like

  today -> too-deh-I

where the last "I" is like the "i" in "ship" and not like the "ee" in "sheep". I agree that it's not a very strong "ee" sound.

[taeric]

I see /təˈdeɪ/ on that page. Per their https://dictionary.cambridge.org/help/phonetics.html page, the eɪ is how they encode what the other site uses ā for. That is, the "ɪ" is not a separate syllable from the "e".

[gus_massa]

I pronounce them in the same syllable, but I used an incorrect notation.