Don't mash and just be patient. I see most Rachels do 5B >2B>5B>2B , 3C or 5B > (winded instant overhead) j.A > etc. All of her blockstrings are relatively easy to block, her 4B is really slow and goes nowhere without wind and her instant overheads assisted by wind. If you really are having a hard time dealing with her pressure, use Counter Assault and regain your momentum. If you don't like the current item you start out with, just Mystic Momo it, It's really good against Rachel no lie, you use it right and you can condition Rachel to be scared of Air Summoning which limits her rushdown potential by quite a lot.