You can follow this itinerary . Day1: Garden By Bay, Singapore flyer, Merlion, Marina bay by sands.All they are near by so you can cover in a day.
Day2: Sentosa Island- palawan beach, Siloso beach, lots of activity is there, Vivo city mall.
Day3: City tour by MRT include Little India,Chaina town, Orchad road, Clarke Quay, Night safary
Day4: Universal Studio Singapore, SEA Aquarium.
Day5:Haji lane, Arab street, bugis, malls for shopping.
Day6: Enjoy and chill in hotel and do shopping more more more..
All places are connected my MRT. So There is no transportation and traffic worries..