YOUR FIRST TOP! You have done a great job! You have taken on some challenging blocks and done remarkably well - corners not cut off, points meeting, etc. And, yes, you will get better with practice. Even after quilting for decades, I am still improving. And, keep remembering, we don't really make mistakes, we are adding design elements and give ourselves challenges! Now, to fix the 'wavies'. Example - top left corner block, take out the side seam and bring it in at a tiny angle to take away half of the wavy (it will be so small, it will not be noticeable when done). Then trim another tiny bit from the outside - no more wavy. Then you should be able to add your borders (sashing is inside, borders are outside) without much problem. You already have figured out why you have a wave, so you probably won't have it on the next quilt. You have a good eye for color and balance and I look forward to seeing your next project.