I have the same problem :oops: I was told to measure everything every step of the way . Turns out a LOT of the patterns I was using actually call for a "scant" 1/4" not a regular 1/4" and that was making all my squares too small :hunf:
And the HST are VERY hard to get correct because of the bias
Practice, Practice, Practice and trust me I know how frustrating it is