Is she trying to call me fat?

here i am in my bed in my extra small old navy t-shirt and my size 1 junior pants. neither of which is tight. then her comes my mother in my room and has the same old navy shirt but in a different print in a size medium cause she says i need to start getting bigger sizes. i cried for an hour in bed. is she trying to say im fat? i am 5 foot 8 inches and 122 pounds my bmi is 18.5 18.5 and below is underweight by the way. so i am kicking my diet up a knotch and for tonights supper i had two appetite cubers and some diet tea. yum. did she try to insult me?