Am I in the wrong to feel mistreated

[BedknobsandBullhooks]

I'm in a relationship of 1 year 6 months.

My last relationship before this was with an alcoholic and was very stressful and just awful, loads of lies involved and left me in a shitty position. I am beginning to wonder what a good relationship looks like, I've never had one.

My partner now is lovely when she's lovely.When she isn't she is capable of blanking me for days
She had left some things at my house including her keys and phone charger and today I took it to her house for her having told her that's what I would do. She never replied tothat message, but when I got there was very shitty with me and didn't even say hello or thanks just took it and walked into the house. I had thought she was at work (as she didn't reply) so I had gone there first and she wasn't happy about this (she's self employed, I know who she works for there wasn't an issue with it).

Her personal hygiene isn't great and this turns me off and I have told her about it. This has only happened recently, latest episode she went almost four days without a shower.

She's generally snappy with me a lot. She shouts when she's annoyed with me. I really try to do nothing wrong but I must do.
My head is just a mess tonight. It was the same last week when she blanked me for days. I can't cope with it.

I don't knowif I am over-sensitive. She always complains of feeling unwell and promised me she woudl go to the GP (I offered to go with her) but hasn't.
I think she might be depressed. We have been planning on moving in together but this behaviour isn't for me. I am nice, I'm always nice to her I'm very rarely anything but.

Is this okay?
I know It's stupid.
Tonight she invited me over and I asked 'could you not be as shitty with me as you were earlier?'

She replied 'forget I asked'. To me that says, 'I'll be as shitty as I want you're not allowed to ask me not to be'.

For clarification purposes only as largely irrelevant, It's a same sex relationship.

You didn't know her before but she will have honed in on you precisely because you are easy going. They are adept at spotting the kind, eager to please ones among us. It's a compliment and also a huge warning sign that you need to learn about setting boundaries for your own well-being, meaning identifying behaviour by others which is beneficial for you and conversely, behaviour you will not tolerate.
The problem is narcissistic personality disorder.
In my experience, when things didn't add up such as on the day you took her keys round and the next day when she was purportedly so busy, it was because my partner was having relationships with others. It may not be the same in your case, however I urge you to realise it's your gut feeling/instinct alerting you when you have a sense of 'it doesn't add up'. Do not ignore your instincts or override them with 'it's probably nothing'.
I recommend ignoring her at the weekend, do not give her any of your attention and do not allow her to think she still has any kind of a hold over you whatsoever, including a notion that you care about her. Before you break it off formally with her can you discreetly tell a few of your friends what went wrong between you because if she is true to type, you need to be prepared for character assassination. What she will probably care about most is winning and her image coming out on top, while making sure yours is trampled. In a tight-knit friendship group she might create all sorts of unpleasant shit stirring for you. You are going to need allies who see through her facade like you have. I'm sorry to worry you but this type of nastiness can happen.

Okay that makes sense. I feel like a teenager here. I know this sort of thing goes on,totally!jvedone a therapy skills course and used to work as an advisor for people returning to work and part of that was training in mental disorders, and I've volunteered as a mental health advisor which again had a course which focused a lot on abusive relationships.
But I have already told a few people in our circle about what's been going on. I was scared to especially as some are equally close to her but their reactions seemed sympathetic. I'll see what happens.

Good luck, I'm glad you now have your eyes opened. It's a shock to discover that, despite your training and thinking you are not naive, it has happened to you aswell. So pleased you are getting out early. Some people waste years/decades before they realise what is happening to them.