A #2 on a 4 tip on your alto is like a #1.5 or #1 on your 5* tip on tenor. If you're used to playing reeds that soft, I disagree with the advice to use much harder reeds. I personally don't see how you could do anything except subtone on an alto/tenor on reeds that soft unless you're 95 years old and have only one lung. You really need to work on your embouchure and breath support.