5days late, multiple symptoms, neg hpt?

ttc...last months period was 3 days late... which was strange but dr explained it away.... this month i ovulated twice (and dont be a prick and tell me its not possible i know when i ovulate)... i am 5 days late now, my have become very sore and tender which never happens, nausues off and on, dizzy spells and headaches off and on, and lower back pain... i just feel weird... not my normal late period feeling... im normaly like clockwork... 28 days last month was first late one in a while... however all hpt have been negative even with first morning urine... help i have no idea whats going on here....