Would my pediatrician make me strip down cause i have my period for the 1st time? can i wear my bra and underwear whenshe checks my breasts and below?

Yes, if ok with you: I recommend a full exam of both breasts and an external genital exam at routine physicals because they are important parts of your body, but using gown and sheets, etc. for partial privacy. It you are not comfortable, share your concern with your doctor, who should respect you. "No" means "No" to doctors too. It is the only way, however, to check a breast lump or genital rash.

Ok to leave them on: It is not typically necessary to undress or be examined just because you are now having periods. You can discuss with your doctor whether you are comfortable undressing for an exam. You can always ask why your doctor thinks it is necessary (if she/he does). It really is up to you.

Make yourself comfy: A superficial genital examination is part of physical check up, especially of young children and adolescents like you who are going through significant changes in body. This is extremely helpful to ensure normal growth and detect any abnormality to offer treatment when necessary. While pediatricians ensure a chaperone for it, request a person of your choice if that would make you more comfortable.