Weight and length are bog all to do with weaning readiness. It's to do with gut maturation. When the gut is ready for solids, it's ready for solids. This probably happens somewhere between 4 and 6 months but if you leave it till they're nearing 6 months AND showing the signs of being ready, then you can let them take the lead. The exterior signs of readiness are believed to mirror the internal maturation of the gut. The signs are...
Sitting unaided
Able to pick up items accurately, put them in their mouth (and then chew and swallow)
Loss of tongue thrust reflex
None of those things are to do with weight. Other stuff like waking up or looking at you eat or chewing their hands or drooling are NOT signs either.
Think about it. Milk is a calorie rich, perfect food for them. Why you'd swap in some mushed up veg and baby rice instead, I don't know. The reduced calorie intake certainly wouldn't help with any perceived notions of hunger.
Think of it this way, I know babies born at 11lbs. Were they nearing weaning readiness? Not at all. It's just a number.
Try and tell yourself that- rightly- milk alone has grown your baby to that size. Because it's that good.
I bf exclusively and weaned dd at 27 weeks. She weighed nearly 26lbs. Milk did that. DS was about 25 weeks and weighed around 22lbs. Milk did that too. Their weights were irrelevant.
The official weaning guidelines are v good, not strict or patronising and offer good info on when and how to wean if you really do want more info.