I GIVE UP ...?

Ok this is really frustrating.

I made my first website in my life a month and a half ago. This was my first introduction to niche sites and seo.
As expected, I made a mistake in choosing my niche. I didn't even know about "exact" and "broad" searches. I only saw the "broad" (on google keyword tool) and saw that it had 50,000 a month. After building my site and reading about SEO, I later learned the "exacts" had only about 200 a month. The keyword was "how to be a pilot in Canada". Anyone who does a search on this keyword will notice how new I am to SEO. My site is pilotincanada.com

In less than 2 months, I changed my main keyword 4 times. I now have done a lot of studying on SEO and consider myself to at least know the basics of it. The keyword now is "pilot license". I changed this about 2 weeks ago. At first, I thought google was just adjusting to the new change. My SERPs were changing everyday, but they would always stay above the 30th page. So one day, I'd be on the 31st page. The next day, I'd be completely off the search (and I checked every page up to page 60). Last week, I was on the 40th page. I kind of suspected the low rankings to be because Google was adjusting my new placement for my new keyword. However, everyday it was not making any progress at all.

Then, all of a sudden, my main page was gone from the rankings. I noticed that my main page had gone away and another page was up, but further back in the SERPS on page 47--pilotincanada.com/private-pilot-license.
This page has 0 backlinks to it. The main page has about 100. Then i noticed that some other long-tail keywords my main page was ranking for disappeared out of the top 100. MY SITE IS STILL INDEXED BY GOOGLE (i caps because i know many of you will tell me to do a site:"mysite" search on google )

What is going on???
Changes I made prior to disappearing from my main keyword ranking...
1. I installed and now am using google chrome (why is this relevant?--read no.2)

2. I read that manually searching everyday on google for your page can affect the rankings. (I usually search through the pages so quickly that a google warning pops out on the screen. I am asked to type in a verification word to prove that I am not a software program)

3. I did start making a lot more backlinks. I am not using any backlinking softwares. i am doing it all manually. So by more, I only mean like 10-15 a day. Whereas before I was only make 4-5 a day.

Could anybody tell me any advice or suggestions on what my site may be going through? Again, my site is pilotincanada.com. The keyword is "pilot license". My site is still indexed by google.

Thank you all. I know it was long read...I appreciate you taking the time to go through it. I am very frustrated and feel like giving up...at least this site and maybe make a new one. But like I said b4, this was my first shot at website/niche/seo and it was a bad first experience