So scared, but I'm not sure why

This is my fourth pregnancy; I have two daughters, had a miscarriage between them and now I'm pregnant again. I got a positive test in early January and haven't seen my OB yet. I'm not vomiting, but I am really tired and feel nauseas every now and then. And I can't stop taking pregnancy tests. I'm not sure if I am scared to lose this baby or what... but I don't know. I just had to get that out. I've tried talking to my husband about it, but he doesn't understand what I'm trying to explain. I don't have many friends and we aren't telling anyone about the pregnancy until I see the OB next week and I see a heartbeat.