Only God knows
I believe, personally that it is not a sin to celebrate secular celebrations such as national day or birthdays. However, you cannot celebrate any religious celebration other than the 2 eids, this is my view.
I could be wrong i could be right, only God knows and may he praise me if im right, and forgive me if im wrong.
Peace
Brother, I have nothing against you, but read what i'm going to post below carefully.
Just because you are innovating into Islam directly, does not mean you can celebrate it. When Prophet (Sallallu Aleyhi Wasalaam) entered medina, he found people celebrating, so he asked them what they were doing, they said they were celebrating what there forefathers were doing or something along those lines, Our Prophet (Sallalu Aleyhi Wasalaam) replied that they should ONLY celebrate the 2 eids, NOTHING else, this is clear as it is.
Infact, our Prophet (Sallalu Aleyhi Wasalaam)said some people among will celebrate days of which the people who came before would do (For example. Christians, Pagans, etc) so that includes Valentines day, birthdays, Christmas etc and on the day of judgement they will be raised up with them! May Allah protect us from this, as we all want to be raised up with the believers.
That's like me saying I will pray 5 times a day, fast during ramadhan, etc but I will also celebrate Christmas but don't' worry I won't include it in Islam, no, it doesn't work like that.
Christmas, Birthdays, Valentines day, New years, ALL HARAM to celebrate.
Do you get the point I'm making? Quit following your desires, and follow pure Islam.
And saying 'Only God knows' is not an excuse, I can say the same for many things, but if it is clear you have to avoid it.