You sound like a right arse, but actually I want to give you a big hug.
I do think it is hard for men to adjust to the new pecking order when a baby arrives; it is of course hard for women too, but especially if a woman is breastfeeding, and dad is working, then mum ends up spending more one-on-one time with baby, and gets used to it quicker.
You need to accept that things have changed. This is forever. But the negativity you feel about it isn't. As your son gets older, is less dependant on your wife, and becomes more of a person that you can relate to, it might not get easier, but it will become more of a two-person thing, and will be more enjoyable.
Check out this book. Its a normal book for normal first time dads, with a sense of humour inserted into it.
Please do not pressure her into feeling she has to return to work or that she should stop breastfeeding. Give her some time to herself when you can; take the baby out for a walk in the buggy, take him to the local library or something, not just for her, but for you as well.
You will have to bite the bullet and accept that some of the luxuries you used to indulge in are now things off the past, and probably would be whether she was working or not.
You need to respect that if she is content "just" being a mother, then she is content. Her happiness is just as important as yours. She is doing a very demanding, tiring, stressful full-time job now - looking after your child! There is no pay, and very little praise, but it is enough for (some) people. I am a full-time mum for health reasons and there are days when I think wistfully about finding a nursery for DS. However, the three hours he spends in a creche when I am training on a Tuesday morning are heart wrenching for me. And actually, I find I enjoy his company a lot; he interacts with me now, and I feel good knowing I am forming him into the person he will become. The smiles and hugs he gives me pay a lot more to my heart than any wages would into my bank.
Have a (carefully worded) conversation with her - you are being very selfish, which you have acknowledged, but you are also obviously miserable. Tell her how you are feeling about missing how things were, but also tell her what a fantastic mother she is.
Good luck, and give yourself a slap for me 