It's fine just watch what you eat going forward.
It shouldn't matter for the foods. My doctor said only no cold meats or soft cheese. I'm not sure about the cat litter thing though. I also didnt know I was pregnant till I was eight weeks, and had been eating all that stuff. The baby lives on the egg yolk for the first 12 weeks, so the doctor told me it would be ok. Now that you know, just try to be a bit more careful. But I have still had that stuff sometimes. Listeria is pretty hard to get so I wouldn't worry too much I'm sure your bub is fine.
I didnt know i was pregnant til i was nearly 19weeks and id been doing and eating alot of things they say u shouldnt, id been out drinking, smoking, riding roller coasters...... i stopped doing it all as soon as i found out i was pregnant and my little girl is perfect :) im sure u will be fine