I think there may be a problem with ironing instead of pressing. If you have lots of bias, they can stretch very easily. But there are ways of fixing that too. Could you show us a pic of the completed block or point us to the pattern please? That will really help us help you with advice.
In your post you say you have completed 2 blocks (correctly??) already but these portions are not coming out right?? If that is the case, can you lay these pieces over the correctly completed ones and see where the problem might be?