Frustrating when attempting to learn how to master a new skillset.
Live fire management on an offset often requires learning, but once figured out, becomes one of those "duh" moments.
If you have a "bed of coals", and you add wood, and then experience problems getting the newly added wood to catch fire, there are clues there.
If you have waited until the wood you had burning, goes to only coals, then you have waited to long to have added wood. Think of having a lit wooden match, and needing to light another before the first one goes out. Use the flame from the first, to light the second. Burning with a flame should be the goal. Add new wood before you lose the flame.
If you have a "bed of coals", and wood that you add does not catch, then most likely, the newly added wood is simply to big. If I get distracted, and don't add wood, and get left with only a "bed of coals", I know that I have to downsize the new fuel that now has to ignite from the contact with the coals. That can be down to the size of a wooden match, depending on how long I was distracted. Once I get flame from that extra small size wood, I can slowly add slightly larger pieces, until I have a small pile of "flaming" wood burning, that can support ignition of my normal size splits.
Beer can size splits (or larger) added after loss of visible flame, will require a robust coal bed, to self ignite. Go smaller to get your flame back, even if you have to use splinter size to start getting your flame back. Then build slowly back up with burning, yes "flaming" wood. That will then allow your normal size splits to catch from a live fire flame.
Offsets require being attentive to live fire management, more so than is expected by new owners. Until you get some experience, pull up a chair, watch some wood burn, and learn when to add wood, before you lose your flame.
If you get more heat from your burning splits than you want, reduce the size. A small fire burning golf ball size splits will give you less heat that beer can size. Adjust the size of your fuel to match your desired temperature.
Stick burning is not for everybody, primarily because of the attention needed to maintain a live fire. There are fire skills needed, but once you figure it out, well worth it.
Just keeping the flame alive during the cook, will require you to adjust the size and frequency of adding fuel. I leave the door half open on my Old Country offset, and manage my temperatures by the size and amount of the splits used.
I couldn't burn the large size splits you have in the picture in my offset. Downsize, and try splitting that piece in your picture into maybe 3 to 4 pieces.