You don’t need a descriptive job title. Seriously. Are you calling yourself a “rockstar developer” or a “CSS ninja”? Let’s stop and think about this for a second. Maybe you’re a freelancer, marketing yourself to potential clients, and so you have a bio on your website and twitter account. Maybe LinkedIn, but I never go there so I wouldn’t know. You decide to add “rockstar” to your job title as a way of telling people how awesome you are at the things you do. “I’m a rockstar designer!”
The problem is that you are the least credible person ever to tell others how good your work is. It’s the equivalent of Budweiser putting “best beer ever brewed” on their label. A company or service provider can tell people they're the best all they want, but it’s just marketing. People know that, and rather than see it as a status symbol or a mark of quality, they see it as self-promotion and professional masturbation.
Do you know what is convincing to people? When others tell them that you’re awesome. Not you, but someone you’ve worked for. When you complete a client’s project, and that client goes and tells three other people that you were amazing to work with and worth every penny you charged, that’s how people know you are worth it.
So go. Be a “rockstar”. But do it quietly, daily, deliberately. Just go do the Work, do it to the very best of your ability, and leave the compliments to the people who know your skills the best — your clients.