I have taken clomid before and I just recently finished up a round of clomid. While I was on clomid I would always ovulate on days 22-25. When I got pregnant with my son back in 2004, my doctor could not give me a due date for the longest time because I did not ovulate on the days that she thought I did. I was almost 13 weeks before she figured out that I ovulated late. I would also get negative OPKs and negative hpts, but I was in fact pregnant. It just may be that your hcg levels are not high enough to be detected by the home tests. I wish you all the best and remember never to lose hope.
Talk to your doc. If you didnt ovulate then she will probobly up your dose next month. How long are your cycles? It still be a late implantation, if you have long cycles. Usually ovulation occurs 14 days PRIOR to your AF, not 14 days AFTER. That only happens if you have perfect 28 day cycles.