No, c'mon, you cannot possibly have any fat on you at 6'1" and 138 lbs.

gee whiz I am a 5'9" woman weighing in just a tad under that and people tell me I am thin as stick. I am too, I can barely keep my usual size 8 leggings up, I am trying to gain my normal weight back. I should be at about 140+. Honestly right now I am between a 6 and 8 but I am too tall to be a size 6 so like you must be right in there also and you are way way too tall to be a ladies size 6.

A 6'1" guy should weigh about 170 to look good (and healthy) in my opinion, even more if he's got great muscles. Keep eating!!!

You sound like this skinny 80 lb 13 year old friend of my daughter's with a 14 inch waist... she'll grab a piece of flabby flesh at her waist because she rarely exercises and say 'see, look, fat!. It's not fat. It's just skin desiring some meat underneath!!