My voice range is way too low for classic metal (D2 - D4 in chestvoice). I've been taking vocal lessons for 3 months and I still can't really sing, hear if I am singing in pitch, or find the melody at all. I am trying to find my mixed voice with little success, trying to be able to sing some Dio songs at least.

Am I just not created to sing, and should alredy give up? I no longer see any possible goals to achieve. It's all too high for me.

PS I know 3 months is not much, but cmon, there is no progress at all
May be you try something way too difficult?

Singing is actually hard for most people who doesn't have good ears naturally 
Try to develop your ears with simple stuf at first before trying to sing if it's challenging for you.

Download some gtp of popular song you like, 
Mark the Vocal line as "S" so that you can hear the notes.
Slow the tempo down.
Select one-two measures and try to find the vocal line on the keyboard or guitar (keyboard is easier)
Check your self with guitar pro.

This is easier and will develop your ears to listen and analyze the high of the pitch
Also it's easier because you can't play on the keyboard out of tune - with voice you can, so your ears will get familiar with right sounds
well, if I could find a popular song I like with such a low voice :/ . I listen mainly to Iron Maiden, Judas Priest, Van Halen..... you see the point.

I tried Dio - Metal will never die, but it's still quite hard, and a few times he goes to an E4 and G4 which is just a bit too high.

Also I don't have Guitar Pro so no vocal "tabs" for me. I may try just analysing the melody and trying to play it on a keyboard or something, I doubt it will help with my shitty range though
Quote by ArturPr
Van Halen

Isn't some of the old stuff with Roth low enough? You don't have to do the crazy screams!

Type O Negative? Peter Steele's voice was pretty low ...
You can do this with MIDI file if you put some of your time to find some simple MIDI player/editor like Garage Band
If you really want to sing of course
And you can transpose MIDI to any comfortable diapason, but I don't see the problem if you transcribing vocal line on keyboard
Three months is basicly nothing. I have been taking vocal lessons for around 4 or 5 years now, and im still no where near as proficient as i would like to be. So just keep at it. Its the same as with guitar, you cant expect to be good after just a few months of practice, you gotta give it it.
That being said, there is a limit to where your voice can comfortably go. You should probably build a solid base and then try to expand your mix and headvoice registers, but chances are, you wont sound like bruce dickinson in any case. I have the same "issue" if you will. My voice is not that high, and altough i did get a few extra tones of range, its still not that impressive. What you will gain, is ease of singing and more control. But just cause you have a lower voice, doesnt mean you cant sing metal. Matt Heafy from trivium has a pretty low voice, and that hasnt stopped him. And if you are looking for classic metal specifically, then look no further than another Iron Maiden singer, Blaze Bayley. He has a much lower and darker voice than Dickinson has, while he didnt really work in the context of the older iron maiden material, he has made some masterpieces on his own. So, the top range of your voice is not what decides if you are a good or bad singer. Its how you use it to craft melodies and parts that counts.

Joža je kul. On ma sirove z dodatki pa hambije.