You did not make mistakes. You made placemats and when you set the table no one will think you did anything other than make them to alternate on purpose unless you chose to share otherwise (I wouldnt). They are pretty and again, size difference the only time that EVER shows up is A) stacked, no one will see them stacked and B) if you lay them out like you just did which again you wont do as well no one sits like that.. even a few inches apart from each other and it wont be noticable at all. AND I have been sewing for a real long time and guess my learning curve is still going up as I do the above as you OFTEN and truly it doesnst matter if you like what you have done. I love what you have done.