There isn't a voice type that is "singing high and low together" unless you are referring to a high belt. High belts are usually Mezzo-sopranos with an upper extention. In opera, there is such thing as a Spinto Soprano, which is a voice that is capable of singing both the lyric and dramatic passages in all registers without amplification. This voice is probably the second rarest of all Sopranos, the first being Dramatic Coloraturas. If you are an aspiring singer, I suggest you look into classical training because that will allow you to branch out in any other genre because of the intense music education you get from it. Giuseppe Verdi was known for composing operas in which the Baritone must have an unusually high tessitura. I'm guessing that you are a Baritone-Tenor, a voice that has a low tessitura but a bright timbre. My brother is the same way. If it hurts to sing some high notes, I'd stay away from them until you get more training. Even at fourteen, your voice is still developing, especially because males start puberty later than females. We won't know what our true voices sound like until we are around the age of twenty-two.
A comment on Big Papa's answer: Renato Bruson and Robert Merrill are great role models for you! If you ever transition into a Tenor, I'd listen to:
Placido Domingo - best Otello ever!
Richard Tucker
Luciano Pavorotti
Jose Carreras
Rolando Villazon
Check out these websites for more information:
singingsuccessonline.com
singingvoicelessons.com
expertvillage.com/voice-lessons
E-mail me if you have any more questions.
Try these exercises, I use them every day in choir and voice lessons.
Breathing:
Place your hands on your diaphragm and breathe out counting to four and breathe in counting to four. Do the same for three, two, then one. This will help you sustain longer notes with a shorter amount of breath. If you don't feel slight pressure from your stomach pushing against your hands, you aren't doing this correctly.
Place your hands on your rib cage and breathe out counting 1 (breathe) 1, 2 (breathe) 1, 2, 3 (breathe)...to 10. By doing this you recognize where your breath support is coming from. If your rib cage does not expand, you are probably using your throat too much and you could damage your voice.
Diction:
Sing scales Do Re Mi...in your comfortable range to a piano in ascending and descending octaves. Over time as your voice gets stronger, you'll be able to stretch your notes on either side of the piano.
Of course La la la always works.
Sing silly words like zingamomma zingamomma zingamomma zingamomma zing zing zing to a piano to sharpen your consonants.
Ah-leh-eh-loo-uh and Mee-meh-maw-moh-moo for vowels.
Humming in the morning also warms up the voice.
Always remember to warm up properly 5-10 minutes before singing. Drink lots of water (at room temperature as to not shock nor relax your vocal cords too much) and keep good posture so air can flow through your body and help you sustain stronger notes. Stretch your arms and neck while warming up to release tension in your upper body. Rest your voice for a few days when you are ill or tired. Be confident and have fun! I hope I helped! Best of luck!