My recent TSH is 3.54. Have fatigue, lack of concentration but no weight gain. Can I still have hypothyroid? Also I might be vit d deficient.

Yes. Not exactly common, but you could have a problem with your TSH production - or the test could be wrong. Should have your free T3 (liothyronine) and Free T4 measured along with a repeat TSH to sort this out. Vit D deficiency remains controversial...
Yes. Many endocrinologists consider a TSH above 3.0 as evidence of hypothyroidism- see http://tinyurl.com/7248c But many with even lower TSH's may be hypothyroid- see http://tinyurl.com/pxz8mkd & http://tinyurl.com/koyamo5 It's important to check your D levels.Most adults become deficient in fall & winter unless taking D.Most need at least 5000 iu of D3/day to attain optimal levels of 50-80.