Hello, i am having light brown mucus (slightly thick mucus), and sometimes a tint of red. could i be pregnant? how soon can i take a pregnancy test?

1 week late: Home pregnancy tests won't turn positive until you're about 1 week late.

3 weeks after sex: Conception occurs within day or so of the sex. It takes about 3 weeks for the embryo to make enough HCG for a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully.