Just started weaning, why is DS not interested in feeding?

[FifiFerusha]

My DS is 5.5 months. For the past week and a half I have been simply trying him out with a few spoonfuls of baby rice, then puree To my shock he was swallowing and enjoying it almost immediately. Over the past two days I introduced carrot purer which he also loved. I have only been giving him a little bit for fun at breakfast time. .maybe only a couple of table spoons, if that. However today he has been really off feeding. He fed a little at 6 .30 am and only spent about a minute on the breast at the rest of today's feeding aprt from a longer one at 4pm. I give him 7oz of formula in the evening which he took. Can introducing solids put them off milk, even if they take only a tiny bit ?

Could he be teething? Maybe his mouth hurts?
But yes, solid food can mean that milk feeds are reduced slightly (not always).
He's still only 5.5 months so I wouldn't start stressing too much over solids. If he takes it fine, if not, also fine!

So, since this post he has obsessively taken to solids and has three meals a day. I didn't intend to move this fast but he seems to really want it but I am worried I am doing it all wrong with regards to portion. He will have about a 70 ml pot of homemade puree depending on meal and this will be mixed with a tiny bit of formula, or porridge or a tiny bit of puréed meat. When he finishes it he opens his mouth for more and tries to hold the spoon in his mouth and gets upset when there is nothing to eat. I just feel like he is wanting to eat too much too quickly though and this is affecting his milk intake. Where once he would bf for 5 to 10 mins I am lucky if he stays on for three or four. Today he outright refused his early evening feed where once he would love that feed. Have I gone too quickly, given him too much? He just seems to love it but I don't know whether to follow his lead as still think his milk intake is very important.

What should an average portion size be for a now over 6 month old?