intense fear

Im absolutely TERRIFIED of being picked up by my boyfriend. He insists all the time that he wants to pick me up or give me a piggyback ride but i'm just so scared of doing it. He gets upset with me sometimes because he says that i think he's weak but that's not the problem. i think im too heavy, not that he's weak. im not even that big realistically, but i think im waaayyy heavier than i actually am (the picture is of me and my boyfriend) i've slowly been able to build up to sitting on his lap but he still wants me to overcome my fear. he's super sweet and reassuring about it, and the other night i almost let him give me a piggyback ride but right before i did it i started having an anxiety attack. im not sure how to overcome this but i really want to. its embarrassing to be so scared of something so small. if anyone has any tips or experiences or anything similar please help a girl out 😩