Well, you have a couple of options, although I don't know of how much use they will be to you once you step outside of booty bay. At your current level, I wouldn't be surprised if mobs aggro to you from miles away.
Nonetheless, you have a few options getting there. The route I took from darkshore was to menethil, then to theramore, and swim north (staying somewhat close to the shore to avoid deep water) all the way up to Ratchet, then taking the boat to Booty Bay. You could also run through ashenvale, and through the barrens untill you once again, reach Ratchet. Although if you're on a pvp server, this will most likely be an interesting affair. Last resort that I'm aware of is to get yourself to westfall and swim south. I'll admit though, I've never tried this particular route and am unsure of it's success rate.
Also note, isn't there a level cap on professions? I'm not sure if level 15 is high enough for expert. Correct me if I'm wrong, but 20 sounds more accurate.