I've done this block before without paper piecing and it was one of my first. I learned a lot about accurate seaming and squaring. You might be needing to use a stylus or a bamboo skewer to help guide the fabric through the feed dogs at the end of your seams (this is where I found I was getting "off"). It also helps to use a "leader" which is a piece of fabric that you sew over before your actual block. I found it helps keep the beginning of your seam more accurate.
Square at every round. Use starch to stabilize the bias and PRESS don't iron because ironing will distort the piece. It will save you a lot of seam ripping in the end. I hope this helps you.