What place(s) did I go wrong

I'm really just a beginner player after just a few months here on chess.com.. I'm trying to start thinking more about position and strategy rather than how I've been playing so far - which is to rely almost totally on tactics.. Here is a game where, in my veiw, "position" was really the deciding factor. 

I'm playinmg black. I lost- felt like I got creamed actually - He used an opening I'd never seen, but I think i actually responed okay in the opening few moves.. I wrote a little about what I was "planning" in terms of position/strategy - note that I was't able to actually achieve any of those strategic goals... What do you think? was I concentrating on the wrong ideas here?  I'd love to see your suggestions/critiques

I disagree partially.  Black's opening was all right... until you fianchettoed the QB.  That created a weakness on e6 that you never took care of and was the source of your tactical issues around move 11.  Either 6...g6 or 6...Ngf6 would have been preferable.  Your control over the center does allow you to lag in development a little bit, so the fact you only have 1 piece out is not too alarming at this point.

I think I would want to play 6...g6, ..Bg7 and ..Nh6 to keep my attention on the long diagonal and also keep the Q looking at g5 where White's KN wants to jump in.  The long-term plan is to castle kingside and expand on the kingside with pawns.  We're playing a reverse color Closed Sicilian.

Thanks for this analysis (both) - I will be reading and re-reading.. very much appreciated..

I do totally get what you're saying about the opening nevae - but I actually read up on it a bit and I think the first 4 or so turns are the main line of this "polish"? opening""" I don't know.. Normally when I see something I simply donÈt know in the opening I just play E5 and develop the center, but this time I decided to read up - a lot of help that was! 

I see exactly what you are saying here... I did it because I was not eager to see him take f5, removing a pawn in front of my king but I should probably have just taken it fxe4?

@greencastleblock: "I think I would want to play 6...g6, ..Bg7 and ..Nh6 to keep my attention on the long diagonal and also keep the Q looking at g5 where White's KN wants to jump in. " 

And that's exactly what he did - I guess allowing that to happen was another mistake....

3. a5 should never have happened, in the sense that it does nothing for you and wastes time you could have used to develop.  Not sure what you were thinking A5 did for you, but it was a waste of time at best.    

More mistakes down the road of course, but just seems like this is an easy one to learn from.  

ArtNJ - Perhaps you are right, but here is what I was thinking.. His next move on that pawn would have been B6. Then whan I wanted to get rid of it I would have had to use my queen otherwise I'd wreck my pawn structure. So I chose to stop the pawn, or let him take mine en passant - which would have put my rook on an open file.. 

I knew there was a good lesson here!  A free pawn > doubled pawns in most circumstances.  Beginners frequently overvalue avoiding doubled pawns.  Him giving you that pawn for free would have been a terrible move.  (A5 doesnt prevent b6 in any event.)

Honestly, I dont think beginners should even be taught that doubled pawns are bad.  Its just way to early for such an exception-ridden rule to be correctly applied, and you see beginners making serious mistakes to avoid doubled pawns literally all the time.