Yay for seeing some improvement!!! You sound like you are going really well . And there is nothing wrong with feed, play, sleep, play - whatever works for you guys LOL!

It's amazing what good sleep does to them. Regarding the 30 minute naps, it sounds like he is waking up after one sleep cycle (most baby sleep cycles range from 30 - 45 minutes on average). It will get better over time, but I found my DS2 would be really cranky if he only slept one cycle, he didn't seem to know how to go back into deep sleep. He would wake up at exactly 40 minutes each time, so I started sneaking into his room a few minutes before his cycle would end and I would watch him. As soon as he stirred slightly (he would usually sigh and move his head) I would start patting his tummy really gently, this would help him get through to the next sleep cycle. It didn't work every time, but it worked for at least one of his 3 naps a day. Eventually he didn't need me to do it anymore, I think I helped him learn how to do it himself

Anyway, that's just a tip from me, your bub may be very happy after his 30 minute nap! They're all so different.

Well done, you sound like you are doing a wonderful job!