Hi and welcome from the sunny state of Florida!!
It seems to me that you're trying to line your blocks up so that they meet even end to end and not where your seams are. Clear as mud right? Especially on the pinwheels and the last set of blocks. Match your seams up(especially on the last set of blocks) and use a pin if you need to and then sew. Square your blocks up after.
You're doing a good job for just starting.