$2 for 4000 impressions? I think you can improve your earnings if you get that much visitors in a month. I checked your site and only saw an ad about experian credit. You must also put text ads where people could find more links related to your site.
congratulation on your first earn and you must keep your blog with fresh contents normally that will push it to high rank in search engines and when you promote your blog ,promote without spam thanks MBeshr