Have you been taking Metformin, by any chance, although I note you are type 1? Metformin is one of the medications that can have an effect on absorption of Vit B12. There are other medications that are linked with Vit B12 deficiency. Also, as one gets older, your chances of having less stomach acidity is increased, which also has an effect on B2.
Having said that, Iron, Folate, Vit D, Thyroid levels that are low can present with very similiar symptoms.
Unfortunately, it seems Health Care Professionals, including doctors, seem to know very little about this so you may not get more than a general check from your GP. However, maybe ask your GP to check all these and then be sure to get a copy of the results, not accepting 'normal' etc.
On a personal note, I'm Vit B12 deficient although my GP said I wasn't, so wouldn't treat me. I'm now self-injecting (GP is aware) and am very much better in energy, mood, motivation and ability etc. Interestingly, my GP, and another GP I see, has noticed the huge change so I'm hoping they might start looking into deficiencies in these Vitamins a bit and take them a bit more seriously.