If you were 8 weeks pregnant, then your HCG levels would have been clearly detectable by now, so the likelihood that you are pregnant is slim to none. There is a number of reasons to be missing your period. Stress, medications, health problems, infections, etc can all affect it.
If you were 8 weeks and pregnant you would show on a blood test. Blood tests test the actual level of hcg in your system and anything over 5 is considered positive. Hcg levels double every 48-72 hours so it doesn't take them long to reach a detectable level.
Samd thing with me . Im thinking its a mind thing or some other issue but why do you feel this way?