Help ease my mind...

I have no symptoms of something being wrong and the baby was doing great 3 weeks ago at my appointment with a very strong heartbeat but i cant get over this gut feeling of something being wrong. My husband says its just nerves since our youngest son is 5 months old and this was unexpected. I called my ob and they said if i have no negative symptoms then everything is more than likely okay.. anyone else feel this way and everything be okay? I have an appointment on the 24th

This is our 4th child