Am I pregnant or is it menopause??? I need your help!?

I am 42 years old. I have had two blood test within the past 48 hours both negative. I have not had a period since Feb, my are tender, my legs itch like crazy, 2-6 EVERY day for about the past month I am nauseous with back pain. My stomach feels heavy and has drastically changed within the past 10 days...yes I have been pregnant before...all the signs are there and my body keeps telling me that is what is going on...but both blood tests can't be wrong can they? The doctor is sending me for a sonogram but I haven't gotten the call yet and I am stressing...I feel like I'm going crazy. My youngest is 17 and getting ready to graduate...we have wanted children always and don't use birth control, but after 17 years we kinda figured we just werent meant to have another one. I keep telling myself that if the blood tests are negative, that means I'm not...BUT...my first born I tested 4 times before I was positive and didn't get that until I was 3mos preg...my youngest @ 4.5 mos