Might be your ADP/agility is too low. As you probably know ADP raises agility, agility raises the number of invincibility frames you get while rolling among other things. Here's a chart that shows the relation:
AGI - iFrames
85 - 8
90 - 9
95 - 10
100 - 12
105 - 13
110 - 13
115 - 15
120 - 16
AFAIK the general consensus at this point is that 20 ADP is optimal and it certainly helps with timings when fighting people from Zimbabwe.