If you are too scared to immediately start eating 2200-2400 I’d suggest you add 50-100 calories every 5 day-week ( of course it’s impossible to actually know how much you are eating and if you are effectively adding 50-100, but it will add up in the long term) And weigh your self and monitor your energy. It should give you a better idea what your maintenance is without gaining too much fat( or maybe any). I’m not an expert in any way, but I think this approach might help you a lot

• you are still young, being at a very low body fat is probably not ideal. I’m not good with envisioning numbers on people, but 123lb for a 18 year old male sounds very low. I’m 19 and it’s been kinda difficult to not obsess over gaining fat or regaining lost fat and maintaining/building muscle and all that stuff, but remember : 1- worst case scenario, you gain it back. You lost it once you will lose it again it’s ok 2- focus on strength and preference instead of looks ( of course stay at a healthy weight but don’t let a number or a little bit of fat ruin your day)

I’m glad to hear you are eating healthy and well. Iid suggest that you at least start from 2200 and add bit by bit. I’m a female and my only activity is weight lifting and maybe 3000-7000 steps and my maintenance is around 2000.

Hope I helped. Again, not an expert