Doubts about Wolff-Parkinson-White Syndrome?

I have always suffered with palpitations. I had check-ups which included scans, ecg, stress tests and 24 hour holter monitors. extrasystoles and not to worry about them too much. So I got used to them. Recently I had a pseudoephedrine tablet for my stuffy nose and I had a huge palpitation that I could feel in my head and made me feel dizzy and lasted 5 seconds. I got worried and went to the cardiologist, he did an ecg and took my blood pressure. He said that the palpitation was a few extrasystoles beating at the same time because the medication is a stimulant he didn't want to do further test because he had results from 1 year and 1/2 ago when he did all the tests.
Now my sister has Wolff-Parkinson-White Syndrome she had an episode when she was 30 years old she passed out and when they did the ecg she was still with the palpitation and with additional test they diagnose the condition. She is OK now she doesn't take any medication aside from that episode she has been fine up until now.
I have worries about me having the condition as palpitations are very difficult to diagnose unless they can check with the monitor the same time as one is having the palpitation. I have read that sometimes it's very difficult to diagnose because it's not that visible. I am very confused and I don't know whether I should ask the cardiologist for more test.