When will i get a proper positive?

I have gotten 3 disappearing positives over the last 2 days followed by one negative. The negative one was however a damaged test. I rang the 800 number and the guy said that the positives mean there was Hcg present...enough to set of the antibodies but not enough to make the dye stick for a long period of time. I'm 10dpo and took the tests on 8 and 9dpo. When will there be enough hcg for me to get a definitive positive? I don't feel like its a positive until the line stays there...even though the guy said the hcg is there.