You said your bike was new so we have to assume it was bought with your height and body in mind. You haven't mentioned any of that? Self fitting is ok IMO but it should be gone into with some general understandings. Your body rests on the bike in 6 spots hands, feet and sit bones. The first thing I like to think about is try standing with your heals against the wall and try leaning forward. You will find you will fall forward as soon as your posture tries to become aerodynamic. Now put a chair out there to rest your hands on and you will feel most of your upper body weight on your hands. that’s the seat forward position. Now move out from the wall and bend over, what naturally happens is your butt moves back and your center of gravity stays over your feet rest your hand on the chair and you can put as little or as much of your weight on your hands as you want the weight is shared between your arms and your core muscles and even legs.
For me it starts with the crank it's fixed then seat height and position to have you balanced over feet and sit bones. Then frame length (top tube) You need to make that hand position last. If your body is totally "proportional" and the bike frame is sized perfect then you are one in a million and the stock setup should work. But for most there has to be some adjustment and the place for that is the bars and stem. Stem will adjust height and reach. Bars can also do both also, but most like to experiment with stems. If your stem has a cover plate that comes off to loosen bar you can try things without even removing bar tape. I like to use an adjustable stem and then after a few weeks of tweaking and I know it's what I want replace it with a fixed setup that has same measurements. But there is nothing wrong with using the adjustable long term. I have a adjustable on my tour bike and it's nice to know if need I can move it while on the road.