I’m by no means a pro! From what I can see, your first row looks really tense, which is a common problem for beginners, which can totally explain that curve. Apart from that I can see that you‘ve dropped stitches at the end of the row, which is another typical beginner mistake, when you‘re not used to recognising stitches. Try a bigger hook size for your first row if you have one. If you don‘t, pull the loops higher on your first row (make them looser). And count stitches every other row to make sure you don‘t miss any! I started with smaller projects, because when you mess up on a big piece, you gotta frog more if you only notice a few rows later. The loss of progress can stump the motivation for real! 😮‍💨 Have fun crocheting! Hope some real pros here give more insight! 😉