Your english is fine from what I've read so far. A lot of the time non native speakers like you believe that their English is sub par, when in fact it is a lot better than that of native speakers. It's just that you have nothing to compare it to so you feel as if you are making mistakes. I honestly would not hire an editor in your case, but if it makes you feel better, you can always find proof reading services on fiverr, or post an ad on craigslist in a university town asking for English majors to proof read articles at $1 to $2 per 500 words. They make some beer money, and you get quality content. Over time you will begin to see what they fix and eventually you will not need an editor any more.
I have to ask though, is there a reason you can not write articles in your own language? I know that North Americans are a huge market and have money to spend on useless stuff from Amazon, but if Amazon delivers to your country, why not try and rank locally. This should not only be easier, but also give you another stream of income from which you could pull for your English site.
P.S: I've always wanted to take a stab at editing and would not mind looking at one or two articles when I have the time if you PM them to me.