Yes, it's Jupiter and you captured all 4 Galilean moons. Jupiter has over 60 moons but your image clearly show the four that are most visible from Earth. Very nice work, especially using a lens and TC.
Image results can vary from night to night depending on atmospheric stability, transparency, etc. Using a TC puts you at a disadvantage for detail but certainly helps with scale. On nights that the atmosphere is turbulent magnification becomes limited in effectiveness. A jumbled or distorted image is only worsened by pushing magnification. A tracking mount would help eliminate movement due to Earth's rotation and that would be one more step toward increasing your odds of better clarity. Then of course you have to factor in optics which a quality refractor telescope would help considerably with. If you are still in pursuit of planets after getting your telescope you might consider a TeleVue Powermate for added magnification. They are a bit pricey but I've owned a couple of barlows to boost magnification and the Powermate is in a league of its own. The quality is incredible. There is an adapter that allows direct attachment to a DSLR and the chrome cylinder of the Powermate/DSLR attach right into the telescope focuser opening.
Also, many of the high resolution planet shots you see on line are photgraphed with modified web cams, stacking hundreds of frames to increase resolution.
