DesignSpark Users, I could use some help - Symmetric Drawing, Mirroring

I have used alot of design software the last couple years, and so far I like DesignSpark Mechanical the best, by far.
Combines the 2D aspects of CAD that I am used to, with the push pull kinda building like SketchUp.

But, there is one main thing I am having alot of trouble with.
Most the stuff I want to design is symmetrical, and it would be alot faster if I could draw just one side of it.
Ive seen some mirror/move operations, and using construction lines, but I still cant seem to get it right.

I want to setup a middle line or plane, and draw, change, move, pull on one side, and it all replicate on the other.
I like doing it that way so I can see the entire part as I draw it,, rather than just drawing half,, then when I am done, mirroring that half over to the other side.

I've had a look and you don't appear to get mirroring in the free version, so no option of live mirroring.

Your best workaround is probably just to do your half sketch and then when you want to mirror it: draw a vertical line about where you want to mirror, go into the 3d view, press move, click on the surface/lines that's been created, move the "move cursor" onto the line and rotate it over 180 degrees.

Hopefully that makes sense, but if not I'll try to explain again :)

That is what was shown in one of the vids, but, without a true mirrow function, that will not work for all situations.

The 3D software hunt has been extremely frustrating. I even have decent experience with some of this stuff, especially 2d CAD, but man, I cant even get the simplest of things accomplished it seems.
Just tried to take an exiting stl file, load it in Designspark, ALL I want to do is make it shorter, but due to its shape, I cant.
In 2D CAD, it would literally be 3 seconds, select half of object, select stretch command, tell it how far. done.

OK, I am done venting...... for now.