Part of the meaning of the number 44 comes from Jesus' earthly ministry. The Lord was crucified and killed on Wednesday, April 5 in 30 A.D. He appears, after being resurrected, eight times to different sets of people. His ninth and last appearance in the flesh takes place on Thursday, May 18. On this day he gives his final instructions to his disciples and then ascends to God's right hand (Acts 1:4 - 12). The period between his crucifixion and his ascension is 44 days.
https://www.biblestudy.org/bibleref/meaning-of-numbers-in-bible/44.html
I looked at that, but as I recall getting to the calculation was nigh on impossible.
It tied Jesus birth to the 1st day of the 7th month - commonly called Tishrei - celebrated per Leviticus 23 on the feast of trumpets. Also celebrated by Jews as the New Year the day believed to be the day of creation. His birth on Trumpets would be the most logical
If it did fall on Sept 11 3BC it does not make 11th September Jesus birthday since the Israelite calendar - God's calendar is based on Luna cycles not solar once, so does not overlay our Roman one.
The situation is more complicated by the way Jews figure intercalary months, which was not God's plan at all. The 1st month of the year is determined by the Barley being abib - ready for harvest before the end of the 12th month in order that the sheaf can be brought to the Temple on the first day of the week in Unleavened Bread - called First Fruits Leviticus Leviticus 23:9ff. If the barley was not ripe for harvest by the end of the 12th month a 13th month was added to ensure First Fruits could be celebrated.
His birthday would be 1st Tishrei each year but that does not correlate to a fixed day in our calendar.
Hope this helps.