Your reference frame is OK, you are doing a lot, and pulling your weight. It sounds like you are both putting in a 100%. But - 100% every day is often not enough with a little kid. It is also extremely exhausting to do it day in and day out for 9 months straight, not to mention 3-4 years that it will likely be needed. It is true that working, travelling, house work, chores, cooking, etc., is a tiring life without a break. But serving a baby/toddler all day long is also a tiring life without a break. It just sucks. When I had to sit and play with the baby, and just watch it, and just do that, and not be able to do anything else during that time... it may sound relaxing, but I could only do that for ~30-45 minutes tops before going stir-crazy. The worst part for me was not being able to do things I like doing for myself, such as thinking. It completely drove me nuts, which made it even more difficult to focus on anything, and it just went like that in circles.
I don't know your wife, but if there is some PPD suspected, it is possible that her 'executive function' is compromised. Executive function is the part of the mind that is in charge of planning, organizing, etc. For example, for me it was difficult to track/use time. I may have been given two hours to do what I want, but I would have problems coming up with what to use it on. It's a little bit like not being able to wind down quickly and focus. So, I may do laundry, because that at least is a productive use of time and it doesn't require thinking. Making calls and interviewing sitters, on the other hand, takes a lot of executive function. So does deciding if you're going to join a fitness club, and which one, and will you do it monthly or purchase a year at a discount, and which classes are offered, and how can you synchronize those with your schedule, and will you be able to do it every week, and now it's another thing to worry about, and... and... and... it's easier to just do the dishes. Of course, sleep deprivation alone can compromise executive function, so there's that.
If the above is a problem, your wife may never be able to verbalize what she wants from you, because the general feeling of deprivation does not come from one specific thing. It's all-encompassing. That's why my first reaction was 'no, you don't need to sit down and talk about how to share the responsibilities, because it's likely that this is not a time allocation problem'. If you sit down to talk, talk about how it is hard for both of you, how you see her work hard, how you appreciate it, etc., and make sure to mention all the work you do in some simple statistic. You don't want to appear to be competing in who-has-it-worse, but it's important to mention how you're trying to help. She may honestly not see all that you do, but may appreciate it if you point it out. Objectively, you are probably both overworked and need to outsource things, but you first need to make her aware of the former, and then suggest the latter. Ask for specific ways that you can help, but don't be surprised if she can't come up with something coherent.
In the meantime, it would probably help if you could tell your wife that every Saturday from 1-4p, you will take care of the baby, and then take the baby out, or better yet, kick the wife out of the house. I imagine it might take her a few weeks to get used to the fact that there is a regular 'me time', and to be able to make a plan for it that doesn't include chores. Depending on your relationship, it may be helpful to brainstorm a list of several things she would like to do in that time, and then pick one for that week. Then nudge her firmly to stick to it, because the decision has already been made. If she feels guilt about the choice to not contribute all the time (or else why wouldn't she agree to hiring a sitter?), it will help if she's not the one making that choice, or at least not on the spot.
Also, look into getting a mom's helper instead of a sitter. 'Helpers' stay with mom in the house and don't provide caregiving, but can cook a bit, clean a bit, launder a bit, and most importantly, sit down and entertain the baby for a while, while mom can do something else (like think :)). These are typically tweens and teens from the neighborhood, they don't cost much, and you don't have to trust them enough to leave the baby with them unsupervised.
I wish you good luck. Statistically, having a kid is the biggest hit a marriage takes. If you can stay on the same side of the problem, it will go a long way. Don't get into a blaming and resentment game. If she starts it, do not engage. Offer acknowledgment, offer to help, ignore personal attacks, and it will eventually pass (when kid is bigger). Think loving thoughts, even if it's not the natural reaction, and do not engage in conflict. Slowly work toward getting housework and childcare help. From your post, you seem to be still doing fine. This paragraph is just in case. Good luck!