Difficulty with low register still after one year

[etc-etc]

Six remedies:

1. Support the low notes with steady flow of air!
2. Decrease the pressure on the lower lip by the headjoint;
3. Adjust your lip position;
4. Adjust the position of the flute vs your lips;
5. Open the throat as if yawning;
6. As a last resort: get a different headjoint.

[andy957]

Thank you for the helpful reply. I'm going to try all six and see what helps.

[Micgalway]

I'm also having a similar problem with C#, C, and B.
For the most part, any sound I get with those three notes is VERY quiet. I haven't been able to get it to the loudness of the other notes.

Good luck - and hang in there

Yes, the sound of these notes are quiet, due to the manufacture of a flute. I found that if I make my lips more oval with the top lip going over the hole (embouchure!) the sound takes another quality. Try altering your mouth by tightening it a bit (i.e. making a faint smile but keeping your lips straight!) or opening it a bit (but not too much; working on a small oval and a pin point small circle will improve the sound ... or not - choose the best of what you find.
That means that if you put your upper lip over the blow hole a little bit more ( say by a 1/3) you will direct the air more into the flute. I don't always succeed ( I am a beginner of 6 months!).
Also, my teacher told me to be careful not to touch the trill keys - little extras in between the keys. A slight touch makes the sound fuzzy. As you grow more familiar with your instrument, you will suddenly become aware of those - you might even try the trill keys for fun! but not for playing low C, etc.
I have a mirror and I look where my mouth goes ( is it better in the centre of the embouchure, or a bit on the side of it?). You have to explore. And give us a progress report! Best of luck.