Great equation for a machine, but a bit tough for mother nature to follow.
To swim well, you'll have to 'RELAX' and feel at home whilst in the water (OW or pool). Are you? I sense panic and anxiety.
4 months to glory is a long time so don't worry, you'll be fine by May to cover your 4K. A 80/20 rule is probably a good starting point for you. That is, 80% drilling and 20% swimming in training; 80% focus on technique and 20% on speed in a lap; 80% confident and 20% adrenaline on race day.