I had a similar problem with baby. he never seemed satisfied. In the end i bought an electric breast pump off ebay. I followed a routine to try and increase my milk supply. Basically I was expressing a couple of ounces in the morning then giving baby the rest.
I was also having a good express in the evening trying to get as much as I could.
I think what sometimes can happen is that when baby is demand feeding he begins by taking little and often. That makes your breasts produce little and often.
What might be happening now is that he is having a little growth spurt and wanting to take more, but as your breasts are still producing a little bit often, he is having to feed constantly just to meet his demands.
If you try expressing a few times a day,band then expressing as much as you can in the evening and maybe getting partner to give baby one expressed bottle before bed so he has a good satisfying feed in the evening and you can have an early night. it fools your breasts into thinking baby has taken more therefore producing big amounts every so often rather than little and often, this will eventually lead to a more satisfying feed for your baby that will allow him to go longer between feeds.
you can speak to your health visitor or bfc but all they told me was "its normal, go with what your baby wants" but this can be so draining and is one of the reasons many women stop.
The book I used was Gina ford's contented little baby book. I dont agree with everything in there but there is a jolly good routine/guideline that should help. I didnt follow to routine exactly as well we all know every baby is different, but it helps you anticipate your babies needs before they get frantic, helps you getting them to have good sleep patterns in the day (not too much not too little). Many people dislike gina ford before reading the books but its not a strict routine like people say, its more gentle encouragement.
My baby who WAS very fretful, and unsettled in the evening, and never seemed satisfied now is very predictable. Sleeps from 8pm to 6am with one 11pm feed. Is no longer overtired and stressed in the day. Its worth a go.
And for people to say that it could be the bottles that cause the breastfeeding problems....I personally dont agree with this. At the end of the day you NEED a break! The expressing is a good idea as baby is still get BM. My baby latched on fine whilst i was breastfeeding, but had bottle as well.
I no longer breastfeed plainly because I didnt make enough effort with breastfeeding. I liked having the freedom of the bottle and I didnt express enough, so I dried up.
But whilst I WAS making enough effort, this really worked for me. Its worth a go anyway.
Hope this helps ;)