If your girlfriend is home a lot of the time. Why isn't she doing more around the house? I feel like she should be helping out with a lot of these tasks to free up your time to work on your side gigs and FT job so you can bring in more money which leads to *drum roll* quicker FIRE!
Why don't you express your dissatisfaction with having to do those chores when you could be doing meaningful work to get you guys closer to ER. Unless I missed something in that OP I just think your GF could do more on her part. It's a team sport!
Seriously!? Have either you or JPO birthed a baby and nursed it all through the night? Do you know how exhausting that is? What about all the hormonal changes the GF is going through? That alone will sap your energy and can lead to post-partum depression which is waaay more common than people think. I hate to say it but she does need more help, support and rest than dad does. Of course that does not change the fact that it can also very hard on him. Dads can actually get their own version of the post partum blues. There are a few things that can mitigate the situation so it doesn't get to that.
OP - I applaud you for being a supportive and helpful partner and dad. This is an extremely hard time in parenthood. Somehow there are people who make it look/sound easy but it ain't - it sure wasn't for my husband and I. We both felt extremely guilty for complaining when we had a lovely baby that actually wasn't a terrible sleeper. But we had to admit that the adjustment was huge! Going from being a carefree couple to having to use our free time just to keep our heads above water with the chores, bill paying, work, etc, was depressing! I now realize that for me, and I think for a lot of people, the first few months of a baby's life are sort of a state of emergency. Here is what I suggest:
1. Never EVER make coffee for your guests again! Or at least until your kid is way older and you're out of this phase. You shouldn't be waiting on other people when they come to your house. They should be there to help you. I know everyone wants to play with the baby so what you should do is say "I'm so glad you're here! I desperately need to go check some emails. Please help yourself to the coffee pot and whatever is in the fridge. Sorry there's not much to eat!" Your guests should get the hint that they need to come over with a meal for you (this is not just for the first few weeks after birth) or with time to help you out a bit. Maybe they can fold some laundry or load the dishwasher. If your family/friends aren't already doing this, consider sending out an SOS email telling people what you need: help with laundry, cleaning, running errands and especially babysitting! Set up a babysitting calendar and see who would like to sign up. If you feel sheepish doing this yourself ask a close friend or relative. My sister did that for me and I had many people sign up to help me. Use your support network!
2. Redefine your dirt model. If you can learn to live with more mess than you were previously used to, this will really help you! One thing that gets really depressing is when you are constantly working but have nothing to show for it. Laundry and dishes just come back and pile up. Instead, try to do the minimum and then move on to something you really want to do in your 'free' time. Go for a walk, read a book, take a bath, go out to lunch, etc.
3. It's ok to pay for help during this time! If you really want to hire a cleaning lady now and then (maybe twice a month?), go for it! If that will improve your state of mind, it is invaluable. Nothing is more important than that right now. You'll be a better partner and father if you feel better. Hiring a babysitter for a regular day of the week might help you feel better also - you can look forward to that day when you can get out of the house and do what you want.
Lastly, I just want to say that it does get better. I always had people telling me things like, just wait till he's crawling/walking/eating solids! Like it was all going to get much worse. In my experience, every milestone made things easier. As the child can entertain him/herself more and more you are also able to get more things done, or even rest a bit while you're with him/her. Then you can use your free time to do things that are fun for you. I used to turn on music and clean the kitchen while my son was crawling around pulling things out of drawers. I made sure there was nothing sharp within reach but decided it wasn't worth worrying about slobber on my spatulas if it kept him happy and exploring (they never seem to like their own toys as much as yours!)
Anyway, much luck to you! You'll soon forget how hard all this was and will be pining for the next one! :)