How do you *know* your highest fertiility day was on the 11th? Are you charting? Are you using ovulation predictor kits?
You should buy the book "taking charge of your fertility" - it will give you good info about how your cycle works.
Typically - you can test at 12 days DPO - that is *typcially* TWO days before you would miss your period. HOWEVER, this assumes that you KNOW when you ovulated because you're charting. You cannot take the "difference between periods" and use that to tell when you are ovulating, because every woman is different.
If you are charting using your temp you will know that you are pregnant the fastest - before the HCG test, because your temp will not drop. Your temp usually drops 4-5 days before your period if you have NOT conceived. If you have conceived your temp will not drop.
I can also tell you this..... try not to "symptom spot" - which means every little "my boobs hurt" you think you're pregnant. Every time you're tired - "it must be because I'm pregnant".... except that you haven't tested yet and wouldn't even be far enough along that you would be having symptoms (which is typicall the 6 week mark - or 2 weeks after you miss your period)!!!!!! I have been pregnant five time and the only time I ever had a bunch of symptoms before I missed my period and was SURE I'd be pregnant was when my tests were negative!!!!!!!!!!
If you KNOW you ovulated on the 11th - timing-wise.....
1. the egg stays in the Fallopian tube for 24 hours waiting to be fertilized.
2. If it's fertilized it stays in the Fallopian tube another 3-4 days.
So at this point - It would be FIVE DPO (days past ovulation), and the fertilized egg is not even implanted yet - which, if you ovulated on the 11th would be the 16th (15th at the earliest).
3. Another week to implant: Your egg can float around your uterus for up to 4 days (Aug 20th), before it attaches. And complete attachment can take up to 4 (Aug 24th) days. That is EIGHT DAYS after the fertilized egg reaches the uterus for your body to begin producing HCG.
It will take a couple days for your body to begin producing enough HCG to register positive on a test.
In my opinion, you should test on the 27th. 25th would be the ABSOLUTE EARLIEST - but be prepared for a negative.
Good Luck