Why does my singing sound bad on my laptop?

So, I've been singing for 2 years now, and I recently got a microphone, an amp with a headphone input, and a pair of Audio Technica ATH-M50x Professional Studio Monitor Headphones. I plug the headphones into the amp, and sing into the microphone, and I sound really good. On pitch a majority of the time, and when I'm not, I fix my pitch and I sound amazing for the rest of the song when I sing. I sang the other day in front of a couple of people, and they told me I had that "raw natural talent." Problem is, when I use my iPhone (4) or my windows 8 ASUS laptop to record myself singing, I sound bad. Not bad as in nasally, or off pitch. Just like, really flat, bland, and like I'm not singing at all. However, when I sing into the mic with my headphones on, I sound really really good. I have full resonance, I don't sound flat or bland, and I even amazed myself with how I sounded. I'm not entirely sure if it's the laptop/phone's microphone's fault, or if it's mine. I'm really confused and I'm starting to get discouraged because this isn't the first time that this has happened before.

Added (1). Haha I've always wanted a mic because I'm a lead vocalist/back up vocalist in my band, so it was a necessity. And the headphones stop the vibrations going in my head so I can hear myself and how my voice is exactly, which is pretty cool. So I personally think it's the laptop/phone's fault, but I wanted more opinions on it

Is it just on the laptop? Maybe its just because you can hear yourself now… I bet you feel silly for investing in a mic now… Ohh

Do you chew gum or smoke cigarettes while singing? - that might make a difference.