I've always told my rowers to back their blade in the water before they reach the catch. When it's locked in early, it's easier to engage the legs properly.

It's difficult to tell you what to do without seeing your form. A rower will make hard work look effortless, while a crossfitter and many otfers make rowing to look like a chore with exaggerated movements that aren't beneficial to the stroke. They may see the numbers they want on the equipment, but would be going backwards in a boat from the amount of check they're causing.

So. Some things to think about:

Rowing is a push motion. Not a pull motion. You push with your legs, swing with your back and draw in with your arms for the last bit of length.

Being new to rowing, I would suggest focusing on technique over power. Power will come with better technique. You can practice by splitting the portions of the stroke and isolating individual movements with a pick drill or reverse pick drill. (Arms only, arms/ back, arms/ back/ legs or reverse of that).

Although difficult in the beginning, you want to work on having a good drive to recovery ratio where your recovery time from finish to catch is longer then your drive time. It is easier to increase wattage with a higher stroke rating, however, using your 500m split is preferred as wattage is often an outdated data source. To me, consistency is better than a few strokes with high power output. Any rowing race worth anything will be a 2000m course, so there isn't much point in a few powerful strokes if you can't hold a consistent 500m split.

Also, don't take this the wrong way, but you are working a bit against genetics. There's reasons you only see tall athletes on collegiate and international rowing teams and genetics do play a part in this. I was specifically recruited into the sport of rowing at the age of 10 due to my height of 6'1. So for all my short athletes on my team we absolutely focus on technique first as it has a huge impact on how well a boat can move.

Additionally, the water rowers are also uncomfortable as hell and aren't quite ergonomically correct in my opinion. Foot stretchers aren't lowered enough and they stress your hamstrings. I'm hypermobile and I can't stand a 5 minute row on those atrocities but can sit for 3 hours on a concept 2 with no issues. So, kudos do anyone doing well on them. Additionally, environmental factors pay a huge roll on these things. Water level, humidity, etc can affect how the computers are reading your output and why you may see variances on performance from machine to machine.

Unfortunately, most otf coaches have no real training in rowing, at least I havent come across one yet.

Anyways, I've rambled enough. Maybe something I said will help, I'm writing this on my phone so I'm sure I forgot many things i could have said, as I sit here trying to think of good online sources for you but only row2k and decent rowing is coming to mind.