I have a 130mm (5") diameter Newtonian reflector with a 650mm focal length (f/5). I have collimated my telescope already but when I'm looking at Mars or Jupiter (not a star I'm sure), all I see is a white dot. Even if I use my 6mm with a 2x barlow, Mars still looks like a white dot but with a liiittle bit of a gray shade like a 3/4 moon. Of course I focused my eyepiece before. Why can't I see Mars or any other planet better than that ?
It seems that you haven't align properly your finder (or) laser. You can align at day with a chimney, but at night you must start with the moon and after that you are sure that you are pointing correctly move to a well known feature (like Pleiades cluster in Taurus) and try to find it with the scope (after that you can move to a star (maybe Mizar in Ursa Mayoris or Albireo in Cygnus if you are in the northern hemisphere) after that you must be sure that the finder and laser are pointing correctly.
Other question is that (probably) you are using a very high magnification with that telescope. I have myself a RTF newtonian 114 / 500 and I usually works with 20 mm eyepice (that is 25x), you are using about 216x that is almost the maximum theorically magnification for that aperture. Maybe you should use the 6 mm eyepiece without the barlow (that is 108x more or less) this should be enough but with cheap optics that could be a very high magnification also. I think that you could try with a bigger eyepiece... maybe 15mm plössl (30x and about 1.5º of size)