Thank you all so much! After looking at a lot of quilts online, I decided I want to quilt a corner stone grid.. But now I'm worried that indeed I will get puckers when adding horizontal lines.. The starching tip is an amazing one, I wished I thought of that earlier. I starched the top of my quilt and ironed it, it looks better now, but I'm still afraid it's not tight enough? But I'm not sure if I try to baste it again I will do any better, me and my friend did three attempts to get it as tight as possible but it's really hard with such a big quilt (and for a beginner (: ) What would you do?
Masking tape is a good idea, I think it will give a better result than using the guide, am going to try that! And thanks for not hating my imperfect first quilt! <3