Looking for a bit of advice on this one.
Me and the girlfriend usually see each other around 4 times a week (we both work in London although we live about 1.5 hours away from each other), however, work has been super busy recently so I've been unable to message/call as much and by the same token, I haven't been able to see her as much. This has caused me a headache in the past because she wants to be able to get in touch and see me whenever I can, which of course worked in university but this is not realistic now that we are both working and things are getting busier. In the past week, I have worked way beyond my normal hours and into the night, however her job isn't keeping her too busy and she often finds herself with free time on her hands. It's also a pressure on me because when we do meet, she'll want to meet as near to 5pm as possible because that's when she finishes whereas the absolute earliest I could ever possibly leave work is 6pm (although I feel 7pm would be more reasonable).
In the past week, we met twice - once for lunch on Tuesday because she was nearby on training and once on Friday for dinner, which I do not think is that unreasonable.
All in all though, this has been a ball ache and on Saturday I decided to spend some time with a few mates (some of which she doesn't like) which caused a massive argument because it apparently meant I would be giving her "slow replies". Come on, slow replies? Who gives a ****? This then led to a huge argument in which I told her she's being immature, my hours will probably only get worse as time goes on and she needs to be more understanding. She then diverted the conversation to my overall attitude and demanded I come home by midnight to talk to her, so that her pre-birthday celebration today doesn't get ruined (yes, I know

). When I refused she also said it is testament to where my priorities are at.
I'm just praying to God her next rotation at work keeps her more busy than the current one because this is getting ridiculous.
Am I being unreasonable? Of course, I have probably subconsciously posted a rosier view of how I've handled the situation (I wasn't nice about it after it entered argument territory because after a stressful week, all I wanted to do is enjoy the bloody weekend).
How do I deal with this in the nicest way possible? She is very sensitive and I can find myself being insensitive if I don't think things through, meaning the whole being 'direct' approach often doesn't work and just sees things descend into an argument.