What Causes Delayed Periods With Frequent Urination And Back Pain?

Hi,
My last menstral period started on February 22nd and My husband and I had unprotected sex on March 5th and March 7th. My period was due on March 22nd but is no where in sight. I have been having back pain, frequent urination, I'm taking naps all day and my appetite has decreased. I am 43 years old but just a tid bit my mom got pregnant with me when she was 40. The urine test that I took on 3/21 and today 3/24 showed a negative result....help