I have had plenty of "best friends" that didn't believe me. Makes me wonder how someone who cared about me could shrug me off when I went up to them and said "I'm a heroin addict I shoot up six times a day". Half the people I told thought I was joking because of what the media portays heroin addicts to be.
Don't let people not taking you seriously make you doubt that you have a problem. I have gone down that road with the thinking of "if noone thinks I have a problem then I must just be being dramatic".
Keep working on your recovery and we're all here for you if you ever need to talk to someone that understands.