Just started fitness for a period of time, chest sizes vary.
It doesn't matter. Just practice normally ... If you still feel uncomfortable, then focus on the small aspects. If you lift dumbbells, you can try to lift them sideways. In the later stage of training, if the intensity reaches a certain level, you can try to add a little protein, such as drinking protein powder or muscle powder, which will help you. You can go to pqfitness to have a look.