Sounds like a learning curve issue or just game frustration to me. Practice your bowling in training mode or 5-over format. You don't want to use too much variation either, rather be consistent and have one or two wicket-taking-tricks up your sleeve when you need to pull it out and confuse your opponent.
Bowling 6 yorkers at midstump per over (not saying you are, just an example) is going to get less wickets than bowling good length and then mixing in some fuller balls and a yorker every so often. Short balls are a bit unpredictable so use them sparingly (I mostly use short balls to throw a 150km/h bouncer at the batsman who just hit me for a boundary). Batsman often won't even swing at balls above the waist in tests, just ducking out the way.
Test matches are always frustrating though dude, you might bowl 10 overs before you even get a whiff at taking someones wicket, that's why its called a test. If you want more action with less patience required, try ODI or even T20. (T20 on CR19 is too much of a slogfest for my liking, ODI has just the right amount of action and defensive balance, in my opinion anyway)
Try and aim for 3-4 dots then start putting the pressure on with your last couple deliveries, that seems to have the best result because the batsman wants to rotate around the end of the over.
If your looking for more information, this is pretty helpful but its a quite a read:
http://www.thecricketmonthly.com/story/1154076/what-is-the-best-length-to-bowl-in-tests
Also make sure your bowling to your field, or change it if its not right. Your style might not suit the field and vice-versa. When bowling, you can change the field the same as the captain so make sure to utilize this as well. If your not great with setting fields, then just try some of the template ones, theres hundreds to choose from.
Yes of course. Not saying for a minute that I expect to get a wicket every ball , and want to bowl out teams for low scores all the time, of course not. Don't mind at all if they score 200 or whatever , but at the same time it's insane if the 200 is made up of say for eg 40 fours and throw in some sixes too . ie. a major percentage of runs in boundaries only. Not to mention having to consider field placements just to try and prevent(often unsuccessfully) the over powered edges that shoot to the boundary. Who knows what's being done about this if anything .