Testing too early??

My ovulation test was positive on the 7th of May. My partner and I were intimate on the 6th. I have tested everyday since Friday. The first two exams were the early detection. Today I used a cheap one from the dollar store. All negative. I am supposed to start on the 26th. My boobs are sore and I have mild cramping that has occurred off and on for the last several days. I am hopeful still but wondered if I might be testing too early?? I don't understand all the acronyms on this site so it's hard to figure this question out... help please?! I am 38 and desperately wanting this baby!