Thank you for asking the query.
You were using a condom during the sex act. And I assume that the condom did not slip or tear during sex. So your partner adequately protected from pregnancy. In addition your partner was having period, and she was on contraceptive pills – This makes a very unfavourable environment for implantation and therefor for pregnancy. Irregular and prolonged bleeding can happen during contraceptive use and this does not necessarily mean the pills are not working. It could be due to excess hormones too.
So to conclude there was many layers of protection and there is no practical risk of pregnancy.
Hope this helps. Please feel free to ask followup questions