No worries dude! Don't beat yourself up over thinking that should be right because how could you know. If you have been cycling for less than two weeks the fact that you are willing to build the bike yourself and having a go at adjusting things as well as being willing to come here and expand your knowledge puts you way above most people I see who can't even do basic maintenance on their bikes and ride around with rusted out chains and the like.
Some jobs on bikes can seem daunting at first but there is so much info out on the internet that if you possess common sense and just an ability to use tools correctly you can do most jobs yourself with a bit of research and trial and error. Generally speaking bikes are fairly simple machines and if you can maintain, adjust and fix the things yourself not only do you save a lot of money, you gain the satisfaction of knowing you did it along with actually knowing your bike well. If you have an issue out in the field you know how a part works and so can better diagnose and fix or at least bodge it together to get yourself home.
Each upgrade you add or problem you fix will add to your overall knowledge of the bike and bikes in general!
Like I said I probably wouldn't bother paying for a bike fit at your stage, I just thought I'd mention it. Local bike shops might offer a cheap version but I wouldn't trust that to be perfectly honest. There are plenty of YouTube videos out there that explain the adjustments and what effects they can have on different parts of your body, if you are having any discomfort in the future then I recommend watching a few, get some ideas of what to change then just get out riding and try out adjustments. Again it is free and you also get to learn your bike more.
For example recently I was getting a bit of knee pain when I cycled 30km plus, so I researched what could be the likely causes and adjusted back and forth over time to get to a better place. In the end I lowered my seat probably around 5mm, moved the seat backwards about the same and adjusted the angle of the seat by a few degrees. All these tiny movements seem inconsequential but I now feel even better on the bike even though I wasn't uncomfortable before then and since I have done many long rides with no knee issues what so ever!
Let us know how it is, I'd be interested how you feel with the difference seen as you don't have a lot of experience. Also feel free to ask any other questions you may have :D