First crochet class

I absolutely loved this class and here is my first finished product. I'm so happy with it but I've noticed my coaster looks a little more 'holey' than everyone else's (if that makes sense lol) and I'm wondering where I'm going wrong. I feel like I'm maybe placing my stitches incorrectly, or if I haven't got the tension quite right? Any and all feedback would be greatly appreciated! Can't wait to make more projects from this page xxx