I'm 5ft 3ins and find most C172s horrible; I either can't see or can't reach the pedals or both. In fact I came fairly near to crashing one on landing very early in my flying career because of this. I was sitting on one cushion and had another cushion behind me, and one slipped. Didn't make for an easy landing! I didn't fly a C172 again for years.
However, the newer 172s have seats which adjustforwards and back, and also up and down, and are just fine.
You can also buy two piece cushions from some company in the USA; they have a part you sit on, and a part that goes behind you, and come in various thicknesses. They look rather good, though I haven't tried one. Bit pricy though. Can't remember who makes them, but you could always do a search.
But the other alternative is....fly something else!!! There are loads of other nice aircraft around. Leave this ridiculously designed, ultimately boring aeroplane for...those who want to fly it.