Need memory on iPhone back

I have an iPhone 6 and it says I have 40 mb of memory out of 16 gb but the memory on my phone isn't adding up. I have deleted apps messages pictures and it remains the same or even shrinks! How can I get the memory I actually have back?

I don't like my birthday gift

I know what you are thinking "what an ungrateful brat!" But please hear me out. Today was mine and my twin sister's 14th. My present was… A book. Yes, I love reading but let me tell a few reasons why I was upset.
1. They didn't actually buy a book they just saw one of my used old books in the attic and decided to give me that. They thought I wouldn't notice. But it has all the markings on it.
2. My twin sister got an iPhone X! I'm not saying I have to have an iPhone but why would they give me MY old book and give her a brand new iPhone?! I asked my mum quietly and she said "Oh my god Stella stop being such an ungrateful brat! You know we're having money problems!"
3. She says we have money problems but she bought my twin an iPhone X and my brother (it's not even his birthday) a smart tv for no damn reason.

I haven't yelled or anything. I know I'm probably being really ungrateful but what are your thoughts on this?

Help me decide. Should I get?

Okay so my iPhone 6 Plus broke, should I get the same phone or get the 6S Plus until I'm able to get a better upgrade that I actually want?

Fix iPhone 6 no service or searching?

So I just got an iPhone 6, one of those used ones they sort of "fix" to make it like new, and I have had it for a few weeks, and it's bern fine. But ever since this morning, it will either say searching or no service. Plus I can't use my cellular data. It won't even show who my carrier is. I updated to iOS 11.1 and 11.1.1 and my phone started workout nvm properly for a few hours, but now it is back to searching or no service. I have hard restarted my phone, reset all settings, updated my phone, and removed and put the SIM card back in. Nothing is Working. Can someone help? I have not yet turned in my broken phone. Would they suspend my account until I send it?