Congratulations and hang in there!
I am in exactly the same boat, lol, after deciding to make a quilt for my friend's 90th birthday. Well, first of all, there was a mistake in the pattern so all my painstaking efforts to cut on-point squares were for nothing. The large, pieced blocks consist of a combination of nine squares of three different patterns. Like you, I have spent all afternoon sewing, unpicking and re-sewing in an effort to get everything to line up correctly, and I am about ready to scream.
Hopefully, we will both get better with practice and spend more time sewing and less time unpicking :D