OP I so identify with this: "DP is wonderful with him, so funny and spontaneous. I want to be just like that too but for now it's 'fake it til you make it'."
I know exactly what you mean about 'fake it till you make it' and feeling weird and hollow about it. The love will come, and it will surprise you, don't worry. Be kind to yourself. You have just gone through the most amazing life change and frankly I don't understand the people who take it all in their stride. My world was turned upside down!
I remember finding it really odd having DS sleeping in our room with us, when I just wanted quiet time with my DH just to rest in those early days after giving birth, BFing at all hours, etc. I felt jealous of the baby for coming between us, and sad I couldn't join my DS in his unconditional love. Not the most mature feelings in the world perhaps, but I felt 'em! And now I love my DS so much if anyone so much as looks askance at him on the bus I would happily kill them. Whereas before I probably would have been happy to give him away to the first granny who showed an interest.
I so know where you're coming from with this too: 'I had a very lazy, indulgent lifestyle before and I have thrown that away now, I can't go back.' I felt/feel the same. The good news is to some extent you can. You have no idea in the sleep-deprived first few months how you could ever go back to your old life but once your DC is older you can go out and see friends, go back to work and work hard if you want to, get drunk, stay up late, etc. When you have PND everyone bleats on about how important it is to 'do something for yourself/have some time for yourself' I totally understand if you think that's impossible now it basically is with a very small baby. But I promise you, it gets better, and easier.
You are doing a good job. Be kind to yourself. I promise you the love will come. Nature sees to it we invest so much time in our DCs that we end up loving them almost by default I think.