I dunno how you practiced them but you gotta practice them in real conversations and of course you gotta monitor your speeches when you are trying to practice them. But there are many speech techniques so I don't recommend changing words, at least it will be likely to lead to some troubles. Maybe you can give metronome a shot: Download a metronome app and practice reading materials following to the pace of it. The steady regimen of metronome is about 15 mins per day, 5 days per week and after 8 weeks you are likely to witness the effectivenesses, and remember that pace should increase from 90 bpm to 120 bpm gradually along the process. Hope that can help u a lot