Happy Fibonacci Day! Background
Today (or Yesterday) is (or was) 11/23 or Fibonacci day! What better way to celebrate than to make a Fibonacci cake?

Examples
3

    ii
i_i_ii_i_i 

&lt;/&gt;
8

              ii              
              ii              
              ii              
              ii              
              ii              
              ii              
              ii              
              ii              
            i ii i            
            i ii i            
            i ii i            
            i ii i            
            i ii i            
          i i ii i i          
          i i ii i i          
          i i ii i i          
        i i i ii i i i        
        i i i ii i i i        
      i i i i ii i i i i      
    i i i i i ii i i i i i    
i_i_i_i_i_i_i_ii_i_i_i_i_i_i_i

Challenge
You're not really making a cake, just the candles because I can't ascii-art a cake
To make the cake you must first get the first n Fibonacci numbers sorted ascending. The candle (i)'s height is determined by value of the current Fibonacci number. The candles are separated by an underscore (_).
The cake should be symmetrical. So the candles should then be flipped and concatenated.
Example Construction
Input: 6
First 6 Fibonacci Numbers: 1, 1, 2, 3, 5, 8
Candle heights:

          i
          i
          i
        i i
        i i
      i i i
    i i i i
i i i i i i
-----------
1 1 2 3 5 8

Output would be:
          ii
          ii
          ii
        i ii i
        i ii i
      i i ii i i
    i i i ii i i i
i_i_i_i_i_ii_i_i_i_i_i 

Reference Fibonacci Numbers
For reference, here are the first 15 Fibonacci numbers. In this challenge, you'll be starting at 1.
1,1,2,3,5,8,13,21,34,55,89,144,233,377,610
J, 58 bytes

3 :''' i_''{~|.|:(,|.)(#&amp;1,2#~0&amp;=)"*}.,0,.(%-.-*:)t.1+i.y'


Uses (%-.-*:)t. for Fibonacci generation. Explanation might come a bit later.

Usage:

   f=.3 :''' i_''{~|.|:(,|.)(#&amp;1,2#~0&amp;=)"*}.,0,.(%-.-*:)t.1+i.y'
   f 5
        ii        
        ii        
      i ii i      
    i i ii i i    
i_i_i_i_ii_i_i_i_i


Try it online here.