When you say they are uneven, what are the measurements? In other words, what are the strips at their widest and at their most narrow? Also, do the strips have pinked edges? If so, how are you measuring -- from the tips or the valleys?
Worst case, if the strips are badly off, you might be able to use them for a different pattern that does not require precision.
If you want to make the particular pattern you have started, then your best bet may be to purchase Moda jelly rolls.