Rowan Soft Baby Yarn - is this the right choice?

I need some advice, please. I am knitting a waxy boxes baby blanket and I am using Rowan Soft Baby. The pattern calls for US 11 circular needles. But as I started knitting, I can see that either the needles are too big or the yarn is too soft (???) because the stitches were kinda loose with apparent holes if I stretch them out (and I am a tight knitter). I checked online and this type of yarn is a worsted weight yarn, which should be okay to knit with only one strand as the pattern recommends. Should I change my needles size and increase the stitches or should I use double strands to make it thicker?

The gauge for this yarn is 4 sts/1 in on size 7 needle!!! And I am using a size 11!!!

What should I do? :shrug:

If you want to use the size 11 needles, you could probably use a double strand but the blanket might come out a little bigger but it would go faster (depending on when the baby is coming!) If you switch to 7 you will need to increase the # of stitches to ge to the same size as the pattern says it will turn out.