Transition baby to bottle with milk?

Ok. I am feeding my 5 month old boy and lately he has been having a hard time starting to eat. I have used a nipple shield since day one. I dont want to pull it off because he is so used to it. The reason is that he was a little premature just about 3 weeks and was in the hospital for that long. But with how my are he couldn't latch on. But anyways, the nipple shield helps. But lately its been hard to get him started. Also he is starting to baby talk and he does that while he eats. Its just a little frustrating for me. I have pumped and have frozen back up. So I defrosted about 3 oz and gave him in a bottle and he had no problem eating it. He had no problem eating it out of the bottle either. Now I want to keep feeding him milk, so that means I have to pump. Now, for me to keep up with him and not have to pump and have him wait for me to give it to him in a bottle, what do I do? He eats about 4 maybe 5 times a day. When I feed him on the , its usually for 20 mins on each side. So I have been pumping about 10 or 11 at night and freezing that. so what should I DO!?? How should I start pumping and still have milk ready for him so he doesn't have to wait?