There are quite a few people on the autism spectrum who're regular members of this site, including me. I certainly wouldn't want to be without my autism. (I see it as giving me a clearer view of the world than others have, without the encumbrance of emotions).
Whether you should tell your family is up to you but, to some extent, it will depend upon your relationship with your family. I'm an elderly guy who hasn't spoken to any of his family for over a decade (and who has no real desire to do so). So telling family members about my autism would be unlikely to make any difference to neither me nor them.
However if, say, you're a teenager still living with your parents and siblings, you have to accept the risk that your parents might just regard your self-diagnosis as being 'just one of those things which mixed-up teenagers go through', rather than taking it seriously. In such a situation I'd suggest asking for help in seeking a formal diagnosis as:
(a) your parents would be more likely to take you seriously, and to welcome you asking for their help ; and
(b) they'd be far more likely to believe a professional diagnosis than one which you'd arrived at yourself.