is it a must to feed my lo cereal? my lo is 9 mths and I haven't given her any cereal. only fruits, vegetables, pasta. am I missing out any nutrients if I don't give her cereal?

It is not a must. It is simply a popular recommended first food as it is easy to digest and has lower risk for allergic reaction (for rice cereal, if I'm not mistaken). Your selection of vegetables, fruits and pasta sounds like a good balance of nutrients. You can consider adding some meat too or protein source like egg or tofu. :)