Yuki, do go the morning market at Whampoa. Try to go before 7 though, as the q will be shorter. The Teochew fishballs noodles, prawn noodles are so good.
In the morning market, there is another smaller hawker centre which only opens for breakfast. There is a stall that occupies 2 units that sells Fishball Noodles which is pretty old school. (you can't miss it, there is always a queue) In the evening, the same stall starts selling Fish Head Steamboat. You may want to try it.
Usually those hawker stalls with long queue are basically more popular in taste. Even for a local like me, I haven’t been to Whampoa food Center in N years…😅
Welcome to Singapore!! Hope u not missing Japan soon. Saw ur video u alway in japan v happy that u n ur family settled down in Singapore. Had fun n also can get into Singapore culture soon.