Everything SQ said is very reasonable and sound, and I totally agree. It may seem extreme to you, but it is correct.
It has been 5 days since we learned your girl is sick. She has likely been sick for longer than that by the sounds of things. We also know your last girl was sick for awhile and ultimately died from an untreated URI.
It is important to get a rat who is actively showing symptoms of a URI to a vet within 48 hours, preferably less.
Rats don't show symptoms until the disease has progressed, they hide it because they are prey animals. Thus, when our rats are showing symptoms it is huge and needs to be addressed immediately.
So a trip to the vet should have been your priority, not going out and buying two more rats (nonetheless that are the opposite sex of your current one when nobody is fixed).
It is 100% reasonable to get into a vet within 48 hours, nonetheless the 5 days that it has been.
A vet will give you antibiotics immediately, it is highly unlikely that you would be delayed in beginning treatment on the day that your rat sees the vet.
Rats begin to feel better (typically) within 3 days of starting antibiotics. So, as of this point, your girl should be on antibiotics and feeling better. But she's not. She was neglected and set aside and you put getting two more rats in front of taking care of her.
Spaying/neutering will obviously take time, but it really should be done if you want to keep two sexes in your home.
Honestly, I'm trying to be as nice and compassionate to your situation as possible, but I feel like you are intentionally neglecting your rats.
I am also starting to feel like you brought your girl to your girlfriend's house so that you could ignore the situation and pretend like it's not your problem. This is because I was under the impression that you would be going to the vet ASAP but now you are responding like you are planning on waiting another week or more.
Rats are great pets, but they require a lot of care. You can plan on your rats needing to see a vet at least once in their lifetime, but more than likely multiple times.
You need to bring them to get treated when they are ill, not just ignore them and go buy replacements.
In this situation, you need to find a vet with more open hours or you need to call it in as an emergency. If you are worried about money, they will work with you on a payment plan.
If you are looking for a new vet, Google all local vets and give them a call and ask if they will see rats.