Bouncing off the ceiling is a great approach and helps a lot to make images look less harsh and 'flashy'. This works well in most residential settings with white ceilings. Try not to overdo it or get too close or your subjects will have dark shadows under eyes & noses. I don't think the Metz 44 af-3p is P-TTL, so it isn't really compatible with your *ist DL's flash metering. It seems likely that it is always firing at full power. It does however have a manual mode that would allow you to manually reduce the power. I believe on your flash there is a 'M' (full output) and a 'MLo' with 1/8 output. Beyond that you can modulate the exposure by changing aperture and ISO. (Shutter speed doesn't have much of an effect on flash because the flash burst is generally of very short duration).
If you want more automation, you probably want a different flash; a P-TTL flash like AF-360FGZ offers the most features and automation, but even a low-cost "Auto thyristor" flash like Pentax AF-280T might offer more automation than the flash you have...but since you already have it, it's probably worth some experimenting with using M/MLo manual flash and learning to use the aperture & ISO to control the exposure.
Unfortunately I don't see a manual specific to the Pentax version on metz.de, but there are
other 44 af-3 here which may help.
Primer -- There are four basic flash modes for Pentax:
M: no automation, sometimes flash output can be manually reduced on the flash. Some flashes have more manual settings than others, yours appears to have 2.
A: Auto thyristor - uses a little sensor built into the flash body to automatically reduce flash power. This system has been around for a long time so there are lots of cheap flashes that offer it. This was the best that most of the manual focus cameras had, though a few such as Super Program and LX supported TTL.
TTL: Through-the lens. Uses sensors in the camera body to automatically dial down flash exposure. Supported by most Pentax autofocus film SLRs. Not supported by most Pentax D-SLRS; only *ist D, DS, and DS2 supported it. Replaced with P-TTL.
P-TTL: Through-the lens but uses pre-flash to determine appropriate flash output. Depending on the flash unit in use also offers high-speed sync, wireless triggering of multiple flashes, and trailing curtain sync. Most Pentax D-SLRs partner best with these flashes. Because these are the newest and in greater demand they are generally more costly.
Hope this helps.