Not gonna scare you but I’ve gone 107 days without a period and not even pregnant at that time. My cycle is usually between 35-40 days on average. Is it due to stress or eating habits recently? Did you have a change of lifestyle? All these could contribute to anovulation. Drink plenty of fluids, exercise regularly and maybe wait for another 2weeks then go doc again to check what’s wrong.
Blood test should be accurate. U cn ask your doc if they can help u induce ur period if ur not preg