My sister in law last lmp 1th October after that 5th she had protected sex by using condoms .her Periods is always irregular. After that she took beta hcg blood test nov 13 ,nov 24 and last one is January 5 which was negative. Then she took deviry 10 mg for 5 days after that 7 days later withdrawal bleeding occurs for 4 days. After that repeat test or not...Is there any possibility of pregnancy after January 5?