Hi Welcome to HealthcareMagic It appears like you have axillary tail of Spence . The Tail of Spence is an extension of the tissue of the breast which extends into the axilla ( right side in your case). The Axillary Tail of Spence is a normal finding in most women. The amount and distribution of the breast tissue that courses up towards the armpit varies from woman to woman. Weight gain and weight loss can make this breast tissues less or more noticeable. During pregnancy due to hormonal changes there is enlargemnt of breast which may be the cause in your case. It ll go away after child birth. take care