I am experiencing dizziness and nausea in regards to certain foods for the past month and a half , i did about 5 pregnancy test an ultra sound and blood test which was all negative.my last period was 21/07. what should my next step be?

See below: 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.