is the French defense really the most aggressive?

I need to find a good opening for black

No.  The French Defense is generally not considered one of the more aggressive responses to e4.

The Sicialian Defense is among the more aggressive. 

Of course, it all depends on how you play them.  Two moves isn't enough to tell.

The French Defense is an extremely ambitious opening strategically... it intends to take control of the game and dictate the play by launching an immediate (move 2) attack on White's e4 square.

'I have never in my life played the French Defence, which is the dullest of all openings.' - Steinitz

Robert James Fischer vs Mikhail Tal (1960) French Drawings (chessgames.com)

'The Defence is anti-positional and weakens the king's side' - Fischer
'at best a second-rate opening' - Carlsen

'After Pawn to King 4, White's game is in its last throws' - Reti (?)

EDIT: Breyer! It was Gyula Breyer, not Reti.

You don't need a better opening for Black, what you need is to study opening concepts and learn more opening theory as you play. Against 1.e4 playing 1...e5 is much better overall. The French defense requires a high level of strategy that you won't really take advantage of yet.

When you get to 2000 elo maybe you can take better advantage of the French defense, although in reality it requires a strategic level close to 2500 to really take advantage of the virtues of the French defense.

Keep playing 1...e5 and study games analyzed by good authors, study opening theory and choose a particular line for each variation. If you accompany all that of studying tactical issues and calculus, also studying concepts of endings, then you will improve a lot without even realizing it.
Also study your own games, you will find your common mistakes and the most frequent mistakes of your opponents.

If at some point you want to get out of your comfort zone, you just have to change some variations and opening lines, you don't necessarily have to stop playing 1...e5.

     It is white that decides how aggressive the French Defence is. Some white players opt for the safest, least aggressive lines for themselves. Black easily achieves equality early in the opening against them--something that is often difficult to obtain otherwise. Of course, it is harder for black to press for an advantage when white is playing defensively from the start, but having chances to develop a positive middlegame plan instead of concentrating on defence is nothing to be sneezed at.

Good job taking it out of context! Fischer’s quote refers to the Winawer specifically, not the whole French Defense. The full Carlsen quote is, “In my younger years I used to consider it at best a second-rate opening…”

He tends to do that a lot... find quotes, and takes them out of context for outrageous effect, and then repeats them over and over and over in the forums.

"Chess can be solved in 5 years"
"Players under 1800 blunder a piece every move"
"Anyone can go from beginner to 2000 in 1 year"

Crap like that.

the french is agressive (maybe agressive is the wrong word and sharp fits better in the mainlines where white plays 3. Nc3 and can be agressive in the advance variation. If you want to play agressive in the Tarrasch 3. Nd2 you have to sacrifice soundness and not play 3. Nd2 c5.

The French has the advantage that you dont have many variations to learn compared to other mainline openings like the sicilian, the caro-kann or e5. in these openings there are many decent sidelines you have to know. the french is really about the classical, the tarrasch, the advance and the exchange  but it also has the disadvantage that besides the exchange variation you really have to know your stuff or you get crushed if your opponents knows his stuff

     Also, Fischer had a relatively poor record vs the Winawer--not as successful as he should have been vs lower-rated players playing what he said was an "unsound" variation. The most notable example was his being crushed right in his pet 4.a3 opening line by unknown IM Kovacevic (using a dated Alatorsev system). He probably didn't quite "get" the Winawer.

The word I used in post #3 above was "ambitious".

@21

"He probably didn't quite get the Winawer."
++ Larsen must have thought that when he decided to play the Winawer against Fischer:

https://www.chessgames.com/perl/chessgame?gid=1044346 

Don't waste your time learning the French Defense unless you're playing as white.  As black, I'd almost never play it.

but you can do a3

The French disaster in 1940 stemmed from the AGGRESSIVE side of their plan. Not from the defensive side. They sent their entire mobile reserve (tanks, motorized Infantry, recon vehicles) into Belgium on an "advance to contact" mission, without solidly guarding the hinge of their turning movement (in the Ardennes), and without first locating the German schwerepunkt.