Because of the small boiler the Gaggia struggles a bit with steaming milk - a 1 hole tip should help a lot! If it is a universal thread you might be able to just change over the tip.
Plus one for the single hole tip. As test you could try blocking one hole with a toothpick.
I see you have fitted the PID - are you using it for brew and steam temps, or just for brewing ?. Does it show the boiler reading while it is coming up to steam temp ?.
A useful method for extending steam time and pressure is to start steaming before the steam light comes on. This will ensure that there is power to the elements during initial steaming, rather than operating only on residual heat, which is what you are doing if you wait until the light comes on.
If you can see the temp on the PID, start steaming at about 130°C. The temp should continue to rise, maybe a bit slower now because you are drawing steam. The steam light may come on before you have finished, and then you will be running on stored pressure, but you should be at least halfway done by then.
If you can't see the temp, check how long it takes for the light to come on after you turn the switch on, then start steaming at about half that time. From memory mine took about 40 seconds, so I would start steaming about 20 secs after flicking the switch.
I found that good foam with a Gaggia was not easy, but it helped to think of it in two stages. The first is stretching the milk, and is best done by keeping the tip JUST below the surface until the milk has expanded enough. This will tend to blow some large bubbles and coarse foam (usually not good), but stage two is to lower the tip a little deeper and work the froth through the milk so it becomes fine foam.