@armando23 >I'm not getting any bigger
That is perfectly normal, especially if you do strength training correctly. You'll be seeing gains eventually, but 99% of all people notice the increase in strength first. For me, it took about 4 months to have a visible increase in my physique. The rule of thumb is anywhere between 4-6 months until you start to see visible changes.
>I have a fat ratio of 3.6 but my belly has no sign of losing fat
Then you did the calculations wrong. Someone with 3.6% body fat has NO fat on his belly at all, and unless you're blessed with naturally godlike pecs, you should be able to almost see your ribs. If you stand perfectly strong and your belly does not retract inwards, you definitely have more than 3% body fat.
General advice: At this stage, you shouldn't stress about your body fat, at all. I'm going out on a whim here, but i'm just assuming you're thin, so you really do not need to stress about your body fat. Men store fat predominantly in the belly, followed by the chest, and then the legs. If you do have some fatty tissue on your belly, and eat regular and healthy, you either have bad posture (very common if you sit a lot, especially in front of PCs) or you're simply just having a little fat on your belly. It will go away by itself.
Building muscle mass requires an excess of calorie intake, which will almost inevitably lead to some sort of fatty tissue, because your body does not have a screen that tells you "i ned XXXX kcal today, feed me THAT exact amount" - even professional bodybuilders alternate between between having 15-30% of body fat off-season, and 3-7% during contest season. If you want the perfectly toned six pack, youÄre not gonna achieve by hungering yourself down to 3% body fat. You need to build that sixpack first, and THEN you can worry about losing excess body fat, which will not be happening anytime soon, so, again, don't stress yourself.
It's far healthier, and better, if you train without worrying about "gains" and "lean" and "bulk" - train to have fun first and foremost! Train to grow stronger! Train to learn to feel your body better! This alone takes time, discipline and practice, and each of these mentioned things have their own rewards. If you don't like your body, you're not gonna be able to change it.
Work with the body, not against it!