Development problems for black after f4 in French Defence I am a French player as black. I am having problems in lines where white advances their e pawn and plays f4 to defend e5. I feel like the break on f6 is useless. I am afraid to castle short. My bad bishop gets trapped and in general I get a misdevelopment of my pieces while I cannot stop white's space opening in queenside.
Here is a game I played today against a FIDE Master (FM).
[FEN &quot;&quot;]
[White &quot;Fide Master Urriza (2289)&quot;]
[Black &quot;Manuel Ignacio Muro Sabater (1637)&quot;]
[startply &quot;9&quot;]

1. e4 e6 2. d4 d5 3. Nd2 Nf6 4. e5 Nfd7 5. f4 c5 6. c3 Nc6 7.Ndf3 cxd4 8. cxd4 Qb6 9. g3  Bb4+ 10. Kf2 f6 (10...g5 {very strong move suggested in answers that opens the position with good perspectives for black})  11. Kg2 Kf7 12. Bd3 Nf8 13. Ne2 Ng6 14. h4 h5 15. a3 Be7 16. b4 Bd7 17. Nc3 Rac8 18. Bb2 a6 19. Na4 Qa7 20. Rf1 f5 21. Nc5 Bxc5 22. dxc5 Nce7 (22...Nge7 23. Ng5+ Ke8 24. Be2 g6) 23. Ng5+ Kf8 Be2 1-0

If I had moved the other knight in words of the FIDE Master &quot;White has still some work&quot;, but my position was suffocating, an engine gives an advantage for white practically all the game.
How could I develop better my pieces in lines with f4 in the French?
You're playing a very sharp opening line that only works thanks to the option of playing 10...g5!. You should only enter this type of position if you're aware of what you're doing. Otherwise you'd be better sticking to quieter, easier positions. If you choose to play a theory-heavy line, then you should definitely know the theory first!