Period almost month late

So I only have one ovary due to the other being removed due to cancer 3 years ago. Doc said I can get preggo just will be harder to. Anyway my periods are pretty regular and I will be a month late in a few days. Took a few hpt and all negative but they were the blue dye ones and I'm hearing bad things about those. So has anyone here ever needed a blood test to know for sure because an hpt didn't work for you? Other than feeling extremely fatigued I feel fine.