Adopting cats doesn't make me as happy as I thought it would

I know it's not something you should say but I thought I really wanted cats and now that I have them ( it's been only few days) I don't feel happy or joy. I like to pet them but it's a weird feeling. I feel a lot of weight on my stomach and I try to make them feel happy and I bought a lot of nice things but I don't feel happy. Is it normal? Should I take them back? Should I wait ?