Thank you everyone, for your input. It's so awesome being able to get opinions of so many people, without leaving home! LOL
I'm starting to get the hang of being "technically correct", in which case the extra border is too much. But on the other hand, I'm also starting to realise (again) that if this is for me, I'm the only one who has to like it. In which case, I'm loving this border! LOL
I laid it out on my bed last night (just all the stars together, no border yet) and it reaches the sides quite nicely, so any border is going to hang down the sides of the bed. And in the picture I've swapped the yellow and white in the little triangles, so there's less yellow and more white. And I do like it.
I'm not entirely convinced I can actually make this border, but I'm going to have a go and make one, then lay it out and see what I think. If I don't like it, I will put it with something else, no doubt.