Hi neochiq - i dont really know much about lymphoma so can't say anthing about that.
Firstly, has your doctor done tests to check ALL your hormones? If not they ought to as that is the only way to rule out problems in the hormone area.
Secondly, get an internal and external pelvic ultra sound done to check for PCOS, fibroids, endometrial thickening and whatever other issues can arrise down there.
Thirdly, get a FULL thyroid check up, eg: TSH, FT4, FT3 and Thyroid Antibodies to rule out a thyroid autoimmune condition.
Fourthly, get a full blood test for whatever else your doctor feels necessary but also include Vitamin D, Ferritin (iron stores), Vitamin B12 and Zinc.
The fact you are gaining weight and have noticed hair growth could indicate PCOS. Weight gain while eating healthy can fit in with thyroid problems too. Low libido could be testosterone deficiency. Low libido could also be linked to thyroid problems. Low libido is also linked to Estrogen excess and night sweats are a symptom of Estrogen deficiency.
Muscle aches and pains are often found with either low Vit D, thyroid problems and estrogen excess.
Tiredness and anxiety is linked to thyroid and excess estrogen. Also people on the anemia board or those with low ferritin have complained of tiredness and anxiety.
The fact your periods have never been regular would definitely point towards hormones, but then again thyroid issues can be blamed too.
As you can see, so many symptoms fall into so many health problems. The best thing is to tell your doctor exactly what you have told the healthboard and hopefully your doctor is a good one and will check all possibilities. Also remember, NOT ALL people with a thyroid condition/ hormone problems, will suffer exact same symptoms. I am hypothyroid and have excess estrogen, but don't put on weight easily. Everybody who knows my situation 'assumes' i'm hyperthyroid. We are all individuals and will experience things differently, but i wouldn't be surprised if your situation was hormone and thyroid related.
Good luck and let us know how your get on. I'd be really interested in knowing what your range of symptoms are linked to