I have a VS card as well that I only use at bath and body works and I haven't gotten an increase yet or even asked for one, I also have an Overstock card and have had it only 4months I think and i used it a few times during the holidays and make normal payments and I got an email yesterday saying that they increased my credit line to $500 from $250 
Small increase and 1st one so far so im happy with how my credit is getting better and scores are going up.