Fat comes in several 'forms' based on where its located.
There are two primary 'types' of fat people who want to lose weight are aiming at.
The first is intramuscular fat. A good example of that is a steak sitting on the store shelf. A 'well marbled' steak has lean red meat with lines of white - that white is intramuscular fat. All mammals (you are a mammal) has that.
Humans, and several other species, but not all, have sub-dermal fat. In whales we call it blubber. In humans we call it just 'fat'.
That sub-dermal fat is there for heat regulation (insulation) and as a secondary fuel supply (when the food runs out you run on your blubber). It also serves chemically, much of the grease and oils in and on your skin are coming from your layer of blubber. Thus the skin (the largest organ of the body) is kept healthy from blubber.
How much blubber you have is not merely a product of how much and what you eat. Genetics plays a huge roll in the ease for you to form and retain blubber. ever meet that skinny guy that can eat anything he wants and still have clearly defined muscles? He is genetically 'hardwired' to not utilize, store and build up a thick layer of blubber.
Then there are the other skinny guys, no matter how thin they are they look soft. I'm one of those guys. I stand roughly 6'1" tall, I used methamphetamine for years, there was one time in my late 20's where I weighed in at 128 pounds. Guess what, no matter how skinny I got, I still looked 'soft'.
The reason being is that I am genetically predisposed to having a layer of blubber. Granted, at 128 pounds my ribs and hips stuck out in boney protrusions, but my skin and that thin layer of blubber 'softened' the bony angles.
Some of us, no matter how hard we try, are not going to have clean, cut definition with only a thin layer of skin over the muscle. There will be that 1/4-3/4 layer of 'fat' under the skin. Stubborn and refusing to go away. always blurring the lines of the muscle and bone beneath.
That mild amount of flab you have may be your optimum body mass as you are genetically destined to have.
You also have to account for your skin type. If you have 'soft' skin - soft to the touch, more subtle skin, chances are that it hangs a bit more loosely on and over your body.
Skin is not readily 'tightened' there are procedures (scalpels sutures, pulling), but there is really no 'natural' way to tighten up the skin. A tad bit of muscle mass growth will tighten the skin, slightly, however over the long term your skin will adjust and 'hang loose'. Unless you make impressive muscle mas growth, growing faster than your skin adjusts.
Most (not all) guys with 'boyish' good looks have soft skin and a thin layer of stubborn blubber. It gives them that boyish charm. The up side is they usually age far slower and far less than the tougher, hardened looking guys. downside they can't get cut without some very serve starvation.
Age also plays a roll. You are 19 still in the tail end of puberty, thus you could still have 'baby fat' which may (or may not) vanish as you hit the mid 20's. Most of us retain a layer of sub-dermal fat until latter in life. It is how the skin stays healthy, how the body regulates temperature.
Since there is only one image of your torso, its a hard call to know if you actually NEED to lose weight (fat). From that one image you look like you are at a healthy mass.
Since you want to bulk up with lean muscle mass, I would suggest you eat to meet the caloric needs of the workout, and NOT eat less than you need. As your muscles grow, you will be burning slightly more calories, and that fat will be exchanged with muscle mass.
Since you are aiming for mass building, its high time you drop the whole 'I will weigh myself to see how fit I am' The scales tell you nothing over your over all fitness. Body fat percentage measurement is the best method. And then the best method to get an accurate measurement of body fat percentage is the displacement method. Being weighed on dry land, then weighed in a pool of water. Fat floats, muscle sinks, the difference in your weight in and out of water can be used to compute body fat percentage.