The main issue is almost certainly light pollution, possibly helped by moonlight. From a bright apartment balcony, faint stars get lost in the sky glow, and with longer exposures that glow overwhelms the frame, making it look white before star trails become useful.

To capture more stars:

• Shoot from a darker location, away from city lights.
• Shoot on a moonless or low-moon night.
• Aim at a richer part of the sky; some regions contain far more stars than others.
• Use a wider lens if possible. On APS-C, something like 10–20mm lets you expose much longer before trails are noticeable.
• Raise ISO if needed; ISO 100 is very low for night sky work.

Why the image turned white:

• The longer shutter didn’t just collect more starlight; it also collected much more ambient sky brightness from artificial lights and/or the moon. That background brightened faster than the stars, so the image washed out.

At 50mm on APS-C, 6 seconds is already short and the field of view is narrow, so it’s not an ideal setup for wide star-field shots unless the sky is very dark.