Is it true that went you do teshuva, and you receive suffering right after it’s actually a good thing because Hashem accepted your teshuva and is erasing your sins? If so, how do you know when it stops? And are you suppose to want it to stop since it’s erasing sins?

We have no clear idea when and why a person suffers or faces challenges. Life is full of challenges, and it is up to us to use all of them to grow, to destine our fate. The connection between tshuva and suffering which you raise is only one of millions of possibilities, but definitely not definite, nor essential. Nothing is automatic nor simplistic. Just remember the parable, like a loving Father does everything towards his child out of love, but the child clearly doesn't always understand why it's in his benefit. Similarly, we accept everything Hashem sends us, believing it's all out of love and for the best!