Universities in Singapore, three national universities, are inaccessible to ordinary people, and private universities are not recognized in China. I suggest you go to other English-speaking countries, such as Britain.

There are two ways: 1. You are a freshman now. You can apply for a three-year undergraduate course in a British university after your freshman year next year, but you have to apply now, because foreign universities have started to apply for places one year in advance. 2. Apply for the preparatory course, and then continue to study undergraduate after finishing the preparatory course. Advantages are less stress and more adaptation period. Other countries basically follow this path.

As for your situation, I suggest you go to a professional study abroad institution for consultation, which is convenient and guaranteed.

You can write privately if you have any questions.