Longer luteal phase TTC

I have a 30 day cycle and ovulated on day 10-11 according to ovulation digital test. I got peak on day 10 so I'm pretty sure i ovulated on day 11 of my cycle. Because I have a longer luteal phase when can I test and get positive?  I tested this morning which is about 11 dpo and got a BFN. Any suggestions or similar experiences? I have been struggling with the fact we have been unable to conceive since my miscarriage. We have been TTC for 3 cycles going on 4. Thanks