sinboi, this is quite normal for born-ins. Some seem to fade out and slip into "the world" with ease, others (usually the more sincere and more devoted) it takes time to adjust to the real world. I myself was born in, a true believer. When i did commit a "sin" by JW standards i felt that was it, im toast at armageddon. And wouldn't turn myself into elders because i didn't trust them.
My advice is just live your life on your terms. If you dont want to do birthdays or xmas then dont. I still haven't done xmas and im 15 months out. This xmas coming up i will but because my little girl will enjoy it. Personally i dont see the appeal of it because i've never had it.
Maybe you could ease yourself into the birthday thing by sending a birthday card or giving a present? What i found helpful was looking at the real reasons why Watchtower condemns certain things. 99.99% of the time it's for control and make you feel less of a person and more of a drone. Rutherford kept getting invited to birthday parties and he, personally, didn't like going to them... so he banned them.
As regards to sex, lets me very honest here... male and female in every animal and species have sex. There's no wedding, no ceremony - they mate. It's natural. It's normal. It's fun. It's fun because you're DNA is programmed with a drive to replicate, because if you didnt replicate the race would die out. This whole idea of sex before marriage being a sin is man made.
Dont feel you need to rush anything. Enjoy your freedom and remember that there's no big scary man up there. And even if there is he's quite the psychopath anyway so i enjoy pissing him off.