Hi Lisa
If you are only 8 days after conception then it is still far to early to say for sure. False positives are rare, but not nonexicstent. My experience with the first responce tests are not good, they dont seem to show as early for me as the clear blue tests even though they claim to. I would wait a few days and I knowthis must be agony for you but there is not much yopu can do.
another point to remember with testing early is that sometimes and eggie can get fetilised but not implant and then inthat case you may get some false hormone levels.
either way I am sorry you are going through this ..please post again and let me know how everything goes.