too early?

I had UPS on the 31st & spotted on the 3rd. Then had UPS on the 13th which is one day before my expected period and spotted on the 21st. But correct me if I'm wrong I was ovulating on the 31st. Now I'm 9 days late with rarely any symptoms. I get nauseous at times. The other day I left work early because I couldn't stand making the food anymore I don't know if it was the smell but I got nausea. I tested on day 5 of being late but got a negative. Could I still be pregnant but took the test too early? If so how much longer should I wait to retest? Has anyone experienced anything like this? I've NEVER missed a period this year. They've always came a week early but I haven't had my period since 19th of March.