Do amphetamines (legal and prescribed, but for that matter,any amphetamines) cause false negative hpts? Keep in mind I am not underweight or obese (thick and healthy) and I have had 1 very light, perfectly scheduled period since possible conception. My dosage of Adderall has gone up and become more consistent since then, (couldnt t always pay pharmacy bill before). I now have weight gain, nausea, and missed a period and swollen breasts all at home tests I ve taken give false. I would be 9 or so weeks at this point and I have had ZERO sexual contact since that day. That i could be pregnant is is impossible right?