How to gain weight but keep training at the same time?

I was almost on the brink of becoming anorexic and being hospitilised. November last year I was 48 kg. It’s now mid-March and I am 5,5 (166cm) and I exercise a lot. I am unsure of my current weight (as mom chucked the scale out) but I assume that it is around 110lbs (50 kg). Almost every day for 1.5+ some times 3 hours. I am a cyclist and have massive dreams of doing the sport professionally. I am serious about overcoming this as it has just seriously just hurt my mother and there is no way I EVER want to put her through that again. I also hate seeing my joints and bruising and hurting easily. Also I get really cold on the bike in the mornings due to low body fat. I am a hill climber and endurance person but I also love the high intensity. I participate in Track, Road and MTB and do pretty well in each. I am just starting to get into racing and I want to become sponsored. But I know that I won’t get there unless I change. I don’t know how much energy I burn but after a ride I think my breakfast energy intake in around 500-600 kj. I just don’t know what to do now. I thought I was getting better as my hair is shiny, my skin is glowing and I’m not afraid of eating food. But today my PE teacher (who’s been helping me a lot) told me it looks like I’ve lost more weight since the beginning of the year. This is a massive blow for me who thought that I was getting better. I refuse to let this rule my life anymore but I just don’t know what to do. I cannot afford a nutritionist and I don’t know what to eat and when. If anyone else has struggled or can help me out please answer. My question is simply, how do I gain weight but keep up my training at the same time?

Anorexia is not going to get it’s claws on me, I am fighting this for my family, friends and for myself and my future!