I have no sense of smell?

It's only recently in the last two years that I've become conscious that I have no sense of smell, at all. I'm not aware of smells around me. For example, if I'm next to a dirty toilet or smell what's supposed to be a stinky sock, or even if someone farts in a room with me, I don't think "Eurgh! What a horrible smell!" Neither do I go out to gardens with lots of what I presume are lovely smelling flowers or walk into a room with air freshener and say "What a nice smell!" You see what I mean. I just don't get it. I can eat food fine, as in picking up different flavours. Is this something I need to go to the doctor about or do I have to live with it? It would be nice to be able to smell flowers and other nice smells. I feel a bit like Patrick from that SpongeBob episode when he gets a nose and can smell.