Hey Joshua,
Hang in there man! I first would like to congratulate you on getting started and doing some deals, many people never get that first deal under their belt. As far as the numbers go, take what you've learned and your actual property numbers and build that cost or variance into the calculators for the next properties you analyze. It's not a perfect science (at least not at first) and the list of things that can go wrong is very long.
For example, I bought a duplex in 2011 and it's been amazing - I have the original tenants, they always pay on time and it cash flowed better than the numbers said. On that same note, I bout another rental last year (SFR) and in the past 12 months I've had more tenant issues than all of my other units combined. Not to mention, 2 months in I had to replace the entire HVAC unit which totally put me in the red right off the bat. You just never know what's going to happen, so take what you've learned, adjust the numbers and stay with it. Even if you aren't making any positive cash flow now, there are still other people paying off your units for you & building your equity... Hope this helps man, keep your head up and keep learning!
