Confused...

I know for sure that I'm pregnant but I don't know how far along I am. I took 2 home tests then went to see my gynecologist and they said I'm 7 weeks (which was 2 weeks ago) but then said I could be earlier than that because the pregnancy test they gave me apparently was showing a faint line. I went to another doctor the other day and they told me, based on the first day of my last period, that I would be between 10-12 weeks. But what's weird to me is that I haven't had any symptoms besides cramping. They told me I might have already lost the baby, which is a sad thought. I go back on Monday to get an ultrasound and confirm everything is good. 
What do you ladies think? Do I have anything to worry about? Has anyone else ever experienced no symptoms? Oh and the other weird thing is I didn't have spotting...but both doctors told me that some women don't experience any symptoms. It just doesn't sit well with me...any wise words or opinions would help to stop my head from spinning lol