Late period - negative test?

Hillary

Hoping someone here may be able to give me some advice... I am 5 days late for my period, my bbt is still elevated, but I took a clear blue digital and first response early result test today and both came back negative? My period has never been late before and we’ve been trying to get pregnant for awhile now. Is it possible I just don’t have enough hcg built up yet or something else is going on??