Denise, stay positive, try not to worry too much until you have had a chance to sit down with your doctor(s) to discuss. You were being proactive in the first place to actually go for your check ups. You've got a running start which most people do not because they choose to ignore rather than know. Your doctors are being proactive too by sending you for an ultrasound. An ultrasound will give them a better look at the tissue for things like size and density if there is a lump.
I am 34 and for the past two years, I have been getting mammograms and ultrasounds every 6 months or so for some suspicious tissue. They have even done a core biopsy which did come back negative. It turns out that it is what they call a fibroadenoma. Even though it is not cancer, I have made the decision that I want it out rather than stressing (much like you are doing now). A lot of women find out they have just dense tissue like others have said before me.
My best advice, is to make sure you keep the lines of communication open with your husband. Don't go the course alone, you are partners. In my case, only my FI and one friend knows know because at the time it all started my Gram was in the last stages of cancer and my Mom was having such a hard time with it. We actually all were. I made the decision that once I knew what I was dealing with I'd tell her rather than add to her or my families stress. Having my FI to support me through it made the world of difference. And BTW, it is OK to cry believe me I did enough of it and then I made up my mind to fight regardless of what it was. You are going to be OK.