Hi Max,
By the sounds of it, you are just not getting the position of the secondary right because you are just eyeballing the secondary through the focuser. This is not accurate enough, and a laser doesn't collimate the secondary. The laser ONLY works for the primary mirror. It took me a long time to understand this.
Eyeballing the secondary through the focuser, you have just too much room for error. The simplest tool for this is the humble cheshire eyepiece.
1: The reason for the long shaft is that you can then slide it in and out of the focuser's draw tube until you have the secondary nicely inside the rim of the Cheshire. You then have a great deal of control over the position of the secondary. You can accurately determine how far left & right, up and down. Once the secondary is centred, only then do you look at the reflectio of the primary in the secondary. The crosshairs of the Cheshire are then used to get the centre dot of the primary all lined up by ONLY using the collimation screws of the secondary.
2: Now you can use your laser. You should just need the slightest tweak of the secondary's collimation knobs to centre the laser into the primary's centre spot. Then all that's left to do is tweak the primary's collimation knobs.
That's it.
The main reason you haven't been able to deal with the secondary effectively is you haven't been able to control the position of the secondary well enough. There are several different 'cheshire' type of tools, and they all do the same thing - deal with the secondary first. The most basic of these is one of the old Kodak plastic film canisters with a hole in the lid and another in the base so you have the secondary mirror sit within the view of the lid's hole. Only once the secondary is set do you begin to consider the primary.
I hope this helps. Let us know how you go.
Mental.