From the pictures is does like slight thinning under direct sunlight but its difficult to say as hair caliber and Characteristics all play apart as Garageland stated I would certainly take pictures and do comparisons , and to add my 2 cents I would go and have a couple of consultations if its really bothering you , I see WHTC are doing consultations in London in November the experts can actually measure your density and also give you Professional advice .
Cheers
Dazz