15 Dpo Some positive, some negative, one inconclusive!!!!?

As far as I know I am 15 Dpo, and still negative result on my preg test strip(supposed to be the most sensitive type). I did get a very faint positive on first response @ 12dpo, followed by an inconclusive blood test...which was not as low as a negative amount of HCG but not quite enough to be a positive blood test. I am just worried that things are progressing normally. Anyone have anything similar happen to them??? Sigh-----