Differentiating menstruation blood with virgin blood

Assalamualaikum. Yesterday was my wedding day. My wife was having her period in the past week but she said it was over and then she did take junub bath or major ablution. But when we start to have sex we realize that there's blood coming out but we're not sure if its virgin blood or menstruation blood. Being a newly wed we continue the intercourse. Only later we started to think that it maybe a menstrual bleeding. What should we do? We know that it's forbidden because we were told about it back in school but never really learn the topic, the hadith, etc. Do you think we should pay Kafarrah? We're financially unstable since we just got married and spent money for the party. Please help us. We don't know where to ask and afraid that our marriage won't be blessed as we broke Allah's rule on our first night. Thank you!!!