Is my house haunted? Or am I paranoid ?

Okay so we recently moved into my grandmas house(she died in 2006, other people moved in but then moved out so we bought it) and a lot of creepy crap is happening. I have been a skeptic all my life and i have never believed in ghosts until now. Whenever i would watch a monster or ghost movie i would get bored because i knew it was fake(this started when i was 8).I'm 15 now and thinking completely different about the paranormal. From the second i walked in i felt like i was being watched, at first i brushed it off that all those restless nights packing had gone to my head. All the time though the feeling surrounds me. Sometimes its so intense i feel like i'm going to vomit. I see things out of the corner of my eye, like shadows or things in the mirror. Sometimes i will lose things and find then days later in a completely different place. I hears footsteps outside my door and voices as well. My dog, who has never done this before, stares at my bedroom wall when there is nothing there, he growls sometimes to. My cat refuses to come inside my house and has become an outdoor cat. I read something online that said to get a digital recorder and ask questions, so i went out and purchased one and did so. I got nothing so i turned it on and left the room. My mom and sister were out shopping and my dad was outside with a friend so i thought it was a perfect time to get evidence. I thought i wouldn't get anything, but when i reviewed the recording the was this weird humming, and towards the end this loud growl. It really scared me and made me question my own sanity. I'm currently trying to get it on my computer. My dad says he had nothing happen to him but that his sisters and his mom said the house was haunted but i thought he was just messing with me. But now i think different. I feel like asking his sisters about they're experiences but i don't want them to think i'm crazy. I think i should go to the library and search the history about the area and the house. My dad hasn't had anything happen to him, but my mom has. She said she sees shadows of people outside the window, and sometimes her door will fling open. The door is a heavy wooden door that's hard to open as is, so wind in not a way to debunk it. My sister who is 7 refuses sleep alone. She says there are people in her room. Really i want to know what to do, i can barely stand this stuff any longer! It makes me terrified to sleep in my own bed or be in my own room!