I’m always a fan of doing what works for you. If having a creamer with your coffee is all it takes to get through the rest of your window without eating, by all means go for it. If you are keeping your CICO in check, you are good. Fasting for many people is purely about limiting the hours they let themselves eat. Celery juice will be more calories but probably still low. It will definitely trigger a digestive response which might keep you feeling hungrier.
If your goals are beyond that and you are interested in the additional benefits fasting can have for your body, then calories of all sorts have to go I’m afraid. Inducing autophagy and giving the digestive system a full break, all need time and no calories to have meaningful effect.
Celery juice is about 100 to 150 cal per cup when I used to track my calories which will most definitely break your fast. While as a juice, it’s relatively low in sugar content and carbohydrates.
However, looking at your plan, consuming creamer, I think you don’t mind having these calories. I see that you are on the time-restricted fast more for calorie restrictions. I’m certain that much creamer will break your fast (mind you a lot of quoted calories are off by a significant margin). So I think if you are already affecting your fast with the creamer, then the celery juice would not be an issue for you.
P.S. This isn’t an attack it’s just a logical approach to your question. I believe that you should do what works for you but at the same time, as an IF community, we are focused on the “fasting” aspect of things and I think a lot of people will point out that the creamer and the celery juice will break your fast.
It breaks a clean fast but you could call it a dirty fast which works fine for some people losing weight. As long as you burn more calories than you eat, you will generally lose weight. I personally prefer to do a clean fast, water and black coffee only, bc even a little bit of something is a slippery slope for me. Best for me to just abstain completely during a fast. Best of luck to you!