No absolutely not, she can stay on Step 1 and indeed she should if she is having these kind of problems.

My MCHN always said that if babies are still being satisfied hunger-wise on the Step 1 there was no need to change up at all and to stay on Step 1 until you changed them to cows milk at 12 months. Step 2 is really only needed for hungrier babies, it is more filling because it is casein-based rather than whey-based like Step 1.

Further, she always recommended that you wait until closer to 8 months before moving up to Step 2 because constipation problems were very common at 6 months when changing, especially when you consider that you are starting solids around the same time.

My DS couldn't cope with Step 2 constipation-wise until he was closer to 9 months - but he was only ever supplemented with formula, I was also bfing him. DD was fully FF'd by 3 months of age and I kept her on Step 1 (Nan Pro Gold) all the way through to 13 months when I got her drinking cows milk and she has always thrived (97th percentile for height, weight and head circumference). I actually think it said on the Nan can that babies who are FF'd from an early age should stay on Step 1 until 12 months.

Chuck out the Step 2 and go back to Step 1!