Hey,
My first quilt didn't look half as good as that!!
You did a great job joining big and little pieces on your first try!!
I found that if I cut on the width of the fabric, when I pieced it sometimes stretched a bit and I got a bigger block than if the pieces were cut on the length.
You will also get trouble with sizes and shapes if you forget and cut on the bias when not needed.
It looks great!!
Next time, try using the quilting needle with the smallest eye your thread will go through well. The smaller needle eye will let you get closer into the ditch in most cases.
Also, use a gentle spreading motion at the seams with your hands as you guide the seam/ditch under the needle, that will help your needle find the ditch as well.
You did great!!!