a dominant lump( any lumps persists for two consecutive menstrual cycle) needs to be evaluated by FNAC (Fine Needle Aspiration Cytology). it will tell weather the lump is malignant or benign. at your age most of the lumps will be benign. after FNAC if it comes as just fibroadenoma
as it has come earlier you need not to worry. if it comees as variants of fibroadenaoma, you may need to undergo surgery, then after ampule of time you may plan pregnancy
. since we do not have sufficient evidence on impact of pregnancy on fibroadenoma you may safely plan pregnacy. i hope this answer is helpful to you.