Welcome! As a JW, I didn't celebrate birthdays for 38 years (hence the name). After quitting 4 years ago, I celebrate everything, with no looking back. Anyway, here's some information with the link if you want to read more:
http://www.jwinfoline.com/Documents/Holidays/pagan_celebrations_allowed.htm
How are new converts instructed?
When a new convert becomes a Jehovah's Witness they are quickly instructed on the pagan origins of our modern day celebrations. The Watchtower has made it known to its followers that they are to reject national holidays, birthdays, mother's and father's day considering them all to be of pagan origin. It is interesting to make a comparison of the rejected celebrations compared to what is allowed for a Jehovah's Witness.
Why aren't birthdays allowed?
Birthdays are not allowed by the Watchtower because two pagan rulers in the Bible killed people on their birthdays. The Pharaoh of Egypt killed his baker (Gen 40:20) and King Herod killed John the Baptist. (Matt 14:6). Is the actions of two wicked rulers sufficient enough proof that God condemns the celebration of birthdays? Is there any evidence in the Bible that proves that a Christian who celebrates a birthday is worthy of eternal death? It is apparent that the forbidding of birthdays did not make it into the ten commandments nor is it listed in the sins that God hates in the New Testament. Don't you think that God would have commented directly on the sin of celebrating birthdays if he provided such a harsh punishment as eternal death?
What is allowed?
Job apparently saw no problem with birthdays as he did not stop his children from regularly celebrating their own special days (Job 1:4,5; 3:1-3). And Abraham had no problem giving a party for Isaac when he was weaned, a celebration of his special day. (Gen 21:8) The Watchtower concludes that since the early church did not celebrate birthdays, we must not either. A birthday is in reality nothing more than an anniversary of a special event. Although the early church did not celebrate birth anniversaries, they did celebrate the anniversary of the death of the saints. The Watchtower allows the celebration of wedding anniversaries which is the celebration of the birth of the marriage. The Watchtower had no problems with celebrating their own 100th anniversary of the birth of their organization. Yet at the same time they disfellowship and condemn to eternal death those who celebrate the anniversary of one's birth. How can one celebrate the birth of an organization but not celebrate the birth of one's mate? Surely if the Watchtower is right, the same God who destroys people forever for celebrating the anniversary of their birth would not thinking lightly of people who celebrate the anniversary of their wedding or the anniversary of an organization's birth.
Are there inconsistencies?
The inconsistency in the Watchtower's rules is highlighted in the marriage celebration. The Watchtower allows wedding rings to be given even though secular sources show that they have a pagan origin. Should they be allowed for Jehovah's Witnesses? Honeymoons are allowed for Jehovah's Witnesses even though they have their origin 4,000 years ago in Babylon with what was then called the "honey month" after the wedding. Perhaps an article will be printed in the future in the Watchtower banning the honeymoon. Jehovah's Witnesses are allowed to use the names of the days and months of the year that are clearly from pagan sources yet celebrating the anniversary of the first coming of the Savior is a definite no-no. Perhaps the Watchtower is waiting until someone reinvents the calendar before they institute a ban on the present Roman calendar. Although the Bible says to honor your father and your mother, the Watchtower says you can't honor them on one particular day - Mother's day or Father's day. If you brought them a card wishing them a happy day on that day or brought them a bouquet of flowers on that particular day, you would be subject to being kicked out of the Watchtower Society and subsequently face eternal death for your actions. Is the Watchtower going beyond what is written in the Bible?