Gosh, I thought I was all pierced-up until I read this thread! *lol* I too love my nose, belly and tongue rings. I had to take off some of the jewelry in my ear so I don't look like I'm all metal.
I had my tongue pierced about a month and a half ago. Before that I was worried, like you, about my job. I talked to my piercer, and he told me I could get it pierced with a retainer (flesh coloured dome instead of a silver ball on top, and the silver ball under the tongue). Honestly, most people didn't know I had my tongue pierced until they saw flashes of silver under my tongue, even then they weren't sure. When it heals (about a month or so), you can screw the bottom retainer and no one will know!!!