Beginning of an eating disorder? How did yours start ?

I am posting this because I think I may be developing an eating disorder. I am a very active person training in competitive sports up to 5h a day (pre covid ) I usually eat a strict , clean diet and have had no issues maintaining this for 8 + years . With covid routine has changed and it's made me focus on the aesthetics rather than performance; I've tried to get lean and lost [edited by 24Help1 for weight] kg . Recently I started dating someone after a long time of being single and I thought it would not have this effect on me again , but it did and I sort of 'relaxed my ways' around them eg enjoy a takeout. I lost control of my eating and drinking habits completely and having realised that (and other things as well they just were not good for me at all ) I've ended the relationship. I can't stop the feasting and fasting cycle and I have become so obsessed with weight it's beyond imagination. It's as if I've realised those foods I were not 'allowed ' exist and I just have zero self control once I have a little of them . This is then followed by fasting amid fear of weight gain . This has gone on two weeks now and I've done my best but I have not worked out anywhere near enough due to feeling sluggish then tired due to fasting . I need to get in in gear as I have applied for a role in the army but I can't seem to stop. This post may read as if I'm a male but no I'm actually female . I think the worst part is the sudden fear of weight gain. Any help on how to break this cycle before it goes too far ?