Babies weighing

Danielle • Proud Mummy to Zachary 2 years old. Married. Baby 2 due Aug 18
My little man is 15 weeks and weighs 15lb6 he was born 7lb 1 .. Health visitors have said he has put on weight too quick so need to make a gp app.. Can anyone relate to this? He has 7oz formula every 3 hours X