If you think you are otherwise perfectly healthy, then if you are OK with not having a sex drive, don't let anyone tell you that you need to have something. I do know various people who don't have sex drives and generally they have been proven to be otherwise healthy (disclaimer: I'm not saying everyone without a sex drive is healthy though). I think it is considered to be a bigger deal in non-asexuals because it causes a lot more interference in relationships and life and the way people think of themselves.

A lot of people say that a person has to be sexual (have a sex drive, have sexual attraction, have a relationship) because that is what is considered to be normal and because often those things make the person speaking to you happy, so by extention they think that by missing those things, you are wrong or are missing out on happiness. They may say those things with the best intentions. If it worries you, then get it checked out if you want to for any underlying cause, but if you are happy without a sex drive, then you can still investigate underlying causes without allowing a doctor to palm you off with libido-raising pills or something. Go with your heart, not someone elses.