It's so understandable you'd be 'symptom spotting' etc, but most women don't even know they're pregnant at 4 weeks! Symptoms tend to start/pick up around the 6-8 week mark I think, and even then may not be what you're expecting. Sometimes women have absolutely nothing but a positive test/ultrasound to confirm until the sprog starts moving.
I was expecting to vomit, have headaches, cravings - everything you see on tv/read about - but I was just really tired at 4 weeks. By 10 weeks my energy was back and the only thing I've really suffered with during the first and second tri this pregnancy is sciatica. I only vomited once this pregnancy and that was at 36 weeks!
Congrats on your pregnancy! x