Replacing Rear Struts

Hello. I have a 2003 Celica GT, and while I am new to working on cars, I am generally a pretty handy person. The problem I noticed I have been having lately is that when I go over a bump or dip in the road, I feel something hit under my seat and it kind of sounds like a grinding. I noticed my ride has been uncomfortable and it feels like every bump I go over is doing damage to my car. After doing a lot of research online I am almost certain that the problem is the rear struts. I ordered 2 KYB Excel-G strut assemblies for the rear and depending on how that goes I will order the front ones later. My concern is whether or not I need to replace the springs as well. I have tried doing the test where you push the car down but honestly I dont know if im doing it wrong or if my shocks are fine because it really doesnt go down all that far. I bought my car used in 2010, and IIRC everything on the car came stock. So for the springs, the tire well does not have enough clearance for my fist. I was wondering if that means its sitting low or if the car just sits like that. I apologize for my lack of experience but any input would be appreciated. tongue