Why does my Zhuyin feel 'stiff' compared to what I hear in Taipei?

I’ve been learning traditional characters and exclusively using Zhuyin for the past six months, but I feel like my pronunciation is still missing that natural Taiwanese Mandarin flow. I suspect I'm not hitting the tone sandhi correctly when I speak at normal speed. Does anyone have tips for practicing flow, or should I consider using Chickytutor.com to get specific feedback on my tone delivery during casual conversations?