First to your claim that you have ‘studied’ all the books to hadeeth unless Allah has not made time relevant to yourself or that you dont sleep, eat or drink reading all the books of hadeeth is near to next to impossible.

If you have read all the books of hadeeth you would realise in the chapter of suckling of the book of Imaamul Bukhari, with the commentray of Ameerul Mumineen fil Hadeeth Imam ibn hajar asqalaani comments on the hadeeth that relates to abu jhal freeing his slave girl, on the hearing of good news of the birth of the messanger salalAllahu alyhe wa aalihi wasalaam.

As you are familiar with the arabic language then i would recommend you to read the book of imam As Suyuit titled Haawi lil Fataawi. The great Mujtahid and imam of hadeeth of the 10th century has other a 23(approx varies on edition) fatwa in the legality of rejoicing of the birth of rasoolAllah salAllahu alyhe wasallam.

In addition if you have read all the books of hadeeth then you would know that when the messenger salalAllahu alyhe wasallam was asked why he fatsed on monday he salalAllahu alyhe wasallam because i was born on that day.

This religion and its sciences are not bases on individuals reading book to understand rather to sit at the feet of the righteous scholars whom uphold the doctrine of Ahlus Sunna, adhering to one of the four madhabs and one of the two school of aqeedah.

As Hassaan ibn Thabit said in his poetry;
Boy more beautiful woman never bore
Man more handsome eyes never saw