Pregnant and bleeding

I'm roughly 4 weeks. Found out last week. I'm 37 and first time pregnant. Had a period last month and found out I was pregnant 2 and a half weeks after I was pregnant. So when I ovulated is in question along with how far along I am. Last night I started spotting, just light pink and there when I wiped. Woke up to a spot in my panties. And still there when I wipe. I'm freaking. So I called dr. and was told to keep an eye on it and pretty don't worry unless I soak a pad. I wore a pad all day and not much but it just feels like I'm on my period kind smells like when I'm on my period. I have had sex last 3 nights. I was also told it could be sex or the embryo attaching. I read it could be my body adjusting. This is about the time I would start my period. I just can't help but think the worst. I haven't had a lot of pregnancy symptoms. Just the peeing really. So I'm worried and trying to stay positive. I googled and read and it's 50/50 on if it's ok or not. It's too early for an ultrasound and I don't go til the 30th and my first dr appointment isn't til November 13th!! Ugh anyone else have anything similar?