There is really nothing wrong with what you are doing if as you say:
There is lots of crema and the taste is great. I do a similar thing which I call a cafe crema (A phrase coined by Alan Frew I think). It is a cross between a long black and an espresso and basically the coffee is ground so that(with an absolutely full portafilter) a double shot will yield 100-120 ml of coffee in ~ 25 seconds. The crema should also be a good hazelnut/chestnut brown and not a pale cream underextracted colour. I must say I prefer to make a coffee this way than add it to water(as for long black).
If you want to make a true espresso as defined by the professionals you need to adjust your grind and volume so that you get about 30 mls in 25-30 seconds for a single or double that in the same time for a "doppio".
This is the beauty of making your own. You can vary the shot to suit your taste at the time.