I'm making my baby blanket out of a Bernat's Cotton Tots and I like it a lot - it is worsted - and 100% cotton. Could you use a double strand (or does the pattern not match up for that?
KnitPicks has Spinnaker 100% Pima cotton - that is super bulky - but again it might not work if there is a "pattern" to show through.
Sorry I can't be more help - I agree with you on the YS owner - why would she send her home with DK when you were looking for Bulky - you'd need what 4 strands of DK to make bulky??