Am I being scammed at my job?

Ok so I’ve worked at my concierge job for a little over a year. I started off full time then went part time because I was a college student and had to go back to classes. I eventually graduated and stayed part time for about a year because we already had a full time person. The full time person eventually would start missing days and needing me to come in early which was fine but it was constant. I’ve had to double work 12 hours and was told about it like the day before. She had an illness but most of her tardiness and abscences were unrelated to that. And she was ungrateful because she “expected” me to cover for her because of her sickness. We were close friends at work but that took a toll on us. So now she has quit and my job has asked me to come full time and everyone thinks they’re doing me a favor but it’s not because I want to eventually leave and use my degree. No raise was discussed and previously I worked a few weekends last minute and they promised me a bonus and I never got it. Plus I’ve been staying later because my shift ends at 4 and they haven’t found a 4-8 person yet. They also promised to do something nice for me because I’ve been helpful and nothing. On the full time persons last day they threw her a big party and got her gifts and I got nothing. I agreed to go full time hastily because the last person quit. My dad thinks I should negotiate a raise. Today I went into my HR managers office and told her that I wanted to try and negotiate a higher salary. She then said the highest they could go was $18.50 / hr ( which is the starting for full time ) and said she thought we agreed upon that ( which I never agreed ) she said she would push for upper management as high as she could go for me but the company had a budget and they had to stay within salary of other communities. I talked to my dad who said she could push if she wanted to and that if I quit they’d be in trouble so they need to push for higher. What do you think?
Am I being scammed at my job?
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