How do I know if my baby is weaning early, or is its breast refusal, or hes not hungry, or its just hot etc? Or if we're giving him too much solids?

DS' feeds are all over the place lately. He generally has 4 a day. He only went from 5 to four about 1-2 months ago, but already the two day feeds are very short (im talking under 5mins in total and sometimes most of that can be one side) if he's bf, and if its EBM hes having only about 100-170ml at each feed.

Morning and night feeds are generally bf unless Im not home, but the night time ones especially are sometimes less than 10 minutes in total (which is very short compared to normal 30-60mins) so then I worry about whether I should be giving him top ups..

Is he dropping another day feed? Is hea weaning? How long do I perservere before I decide its not temporary?

ds1 was ff from 6 months so it was a lot clearer how muchmilk he was getting, but this is confusing. I keep reading that he should be still having 600-900ml a day and I just cant see that hes having close to that.