Yeah unfortunately I dare say it sounds like the above is right... That said, Mars is very very difficult to view through a dob, I've had a 12" dob for about 3 years and I've never managed to get a good look at it. Venus also does not have a "surface" you will see, it is perpetually covered by a dense layer of pale cloud. The interesting thing about it is you should be able to see a "phase" to venus, like the phases of the moon. Saturn and Jupiter on a good night are fantastic! But good nights aren't frequent, and yes, it does take a lot of patience and trial and error to get it for more then a few seconds in the eye piece. It does sound like maybe your bearings need a little bit of work to get smooth if you are getting a lot mexican jumping beans. This website is a decent representation of what you can actually expect to see at the eye piece.
http://www.backyardvoyager.com/eyepieceviews.html
In fact, I'd actually call most of those "above average" to what I normally see, but I rarely get out to very dark skies..
If I were you I would definitely give it one more go, like the above suggests, it does get easier with experience, not harder, so if you can find Saturn and eta c or orion, hunt out 47 tuc or omega centaurus, and if you are still not impressed, pack it in. Nothing wrong with that, this hobby certainly isn't for everyone, straining to see some faint smudge with averted vision I sometimes wonder myself why I do it.