I am not sure but I think my Golden Retreiver may be pregnant. Is there any possible way to tell if she is without taking her to the vet?

Unless you know an experienced breeder who knows what to feel for, and could palpate her abdomen at the correct time, probably not. At least not until she's far enough along that it becomes obvious.

But if you suspect she may be pregnant, you should have your vet check her over. Besides confirming the pregnancy, your vet can discuss the various "what to do if..." situations that you need to be prepared for.