This is leading into an interesting study. Again thank you.
The adjective, adzumos, is a definition describing whatever it is applied to. Literally, the Passover feast (one day) is "unleavened" and the period after is entirely "unleavened." The "feast of weeks" fifty days after, becomes the first day of the rest of the "unleavened" portion of the year.
The bread for the Jewish passover meal (which was conducted on the wee hours of 15 Nisan, on which day Jesus' body had just been entombed but not spiced with myrrh and aloes) had to be baked just moments before that meal, and not on the day before the evening of the upper room supper meal, which had commenced at nightfall of the eve of the day before--14 Nisan--in which the lambs are killed (as was Jesus, the Lamb of The God), just before sundown of the 14th while the preparations for the Jewish passover were taking place.
You might want to look these up:
Mat_27:62 Now the next day*, that followed the day of the preparation, the chief priests and Pharisees came together unto Pilate,
Mar_15:42 And now when the even was come, because it was the preparation, that is, the day before the sabbath,
Luk_23:54 And that day was the preparation, and the sabbath drew on.
Joh_19:14 And it was the preparation of the passover, and about the sixth hour: and he saith unto the Jews, Behold your King!
Joh_19:31 The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was an high day,) besought Pilate that their legs might be broken, and that they might be taken away.
Joh_19:42 There laid they Jesus therefore because of the Jews' preparation day; for the sepulchre was nigh at hand.
* = "the next day" had to be the week's Sabbath; that is, 15 Nisan
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Note that the Passover feast--a sabbath--in this particular year fell on the ordinary last-day-of-the "week" of seven days Sabbath. Therefore it was s double sabbath, a very special Holy Day, with three events, according to Adam Clarke, the commentator:
For that Sabbath day was a high day -
1. Because it was the Sabbath.
2. Because it was the day on which all the people presented themselves in the temple according to the command, Ex. 23:17.
3. Because that was the day on which the sheaf of the first fruits was offered, according to the command, Lev. 23:10,11. So that upon this day there happened to be three solemnities in one.(ref. Lightfoot.) It might be properly called a high day, because the passover fell on that Sabbath.
And that is whe the crucifixion could only have taken place in the year reckoned by our calendar, in 33 Anno Domini.
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Since the preparation did not begin before the ninth hour, 3:00 PM our reckoning, and must be finished before the 12th hour (6:00 PM), the bread had to be made and instantly baked in that time to BE "unleavened," or technically more properly "unrisen" (since some form of leavening must have indeliberately incorporated during its unsanitary mixing); otherwise if it stood around even a bit, it was then considered as having been acted on by the airborne , water-borne, or hand-borne microorganisms apart from intentionally and usually leavened with starter dough; and was therefore unfit for the meal to be conducted later after dark.
Remember, the killed lambs still had to be bled out and cooked before sundown, 6 PM, after which "picking up of sticks" was a deadly activity.
So there is no reason that the LORD's Upper Room Supper would not have comprised starter-dough-raised pita bread, Jesus blessing The Father for it, broken, and passed around to everyone there.
Hope this helps understand why the eneucharacterization of the wafer does not sound feasible or representative of the Last Supper.