Eaten haram mistakenly

As salamalikum warahmatullahi wabarakatu, I moved to UK in 2017 from Saudi Arabia and because it was my first time for studies. I had no clue what to look for in food to deem it haram accept for pork and alcohol. On my first week I brought frozen pizza, that had pork pepperoni on it when I saw that I removed the pork and ate the pizza because I wasn't aware of the contamination issue just like that I have made few mistakes here and there where I had no idea at all that the thing could even contain haram ingredients. I am just very guilty and don't know how to overcome this guilt. Will this be recorded as a sin for me and is there a way I can undo the effect in my body? Jazak Allah