If something starts or ends without the 1/4 seam line being correct...NOW is the time to STOP and do it over. Always make the corrections as soon as you notice a problem and you will save yourself lots of time and frustration later.
You should have a gap to trim the pieces apart. Make sure you do not trim your fabric! Only the thread.
Press all pieces open. Press the seam toward the darker fabric. Trim the tabs off to achieve the square look.
Once the pieces are pressed replace them in the block lay-out. I took this picture without trimming the tabs off, but I did trim them off before joining the squares together.
Chaining saves you time walking back and forth between the machine and the ironing space and the time leaving the machine and coming back again and again. It also saves the thread that would be wasted to start and end pieces that are done by themselves.