It's really tough about the food isn't it? I decided to give it a go precisely because of things like the coordination, and dd can just about sit up, not totally independently but is rock steady in her bumbo. She also shows a real interest in food when I eat and would have weaned herself on cake anything she could grab from my plate by now if I had let her. She was also very obviously hungry, especially in the afternoons, feeding hourly and clearly not satisfied.
It wasn't an easy decision though. I too thought it was a growth spurt but it's been going on for 3 weeks or more now, and a spurt should mean you catch up in days. I also did a lot of research into why the recommendation has changed to 6 months and not a mouthful before. Most of it seems to be connected to gut immaturity leading to allergies. However a friend of mine has both her children under the care of the country's leading allergy specialist and he doesn't agree with this at all, maintaining that allergies to common foodstuffs is primarily genetic. He encouraged her to wean them before 6 months. Also, the basis for the research of the EAT study is that food should be given in very small quantities from 3 months to prevent allergy. I was going to enrol dd in it but then started giving her formula in the evenings so she no longer qualified. There is no way that they would have received permission to carry out the study if it was believed that there was any risk of real harm.
Remember though that my dd was nearly 2 weeks late and wasn't your DS early? So although born a week apart there is a bigger gap.
I doubt though that food or formula will be the sole answer, if an answer at all. Dd has had a formula bottle before bed since she was about 10 weeks. She has never slept well. After her food yesterday she didn't sleep any more than usual.
In the end every baby is different, as is every parent. I really didn't think I would be happy bending current guidelines but through talking to the health visitor and others have come to the conclusion that it was worth trying. I can always stop if it doesn't go well.