Not really more difficult.

More coffee + same grind + same amount of water = more dwell time for the water. Of course the coffee will taste different. Ditto if you're using more coffee + same grind + more water. Make major changes in any of the basic paramters and you'll get big differences in the cup. Adjusting technique to match circumstances is one of the challenges and joys of espresso.

Tasting "overextracted," doesn't necessarily mean overextracted. You'll have to fool around and see what helps. A good place to start is with the grinder -- in your case you might want to try a coarser grind.

Are you overdosing your basket? Possibly. The overfill and swipe method works better for some baskets than other. It's not restricted to double vs triple. Good enough scales are widely available for less than $15. You may want to purchase one to check. Bear in mind that there is no single right weight -- not even for a given basket. You're playing with dose and headroom -- either of which is capable of moving the taste needle a lot.

Like all the other measuring equipment home baristas use to soothe their OCDs, the best a scale can do is provide some reference points -- not a lot of Eureka moments.

BDL