Too many options to choose from and it’s confusing…
you’re 23.
White?
5 or 10 mcg will do ya.
I’m Hispanic 
10mcg is a sensible starting dose - That way you can cover a reasonable dose range with just a few sprays.
Stick to 6% Neroli for scent - Its a good diffuser and easy to cover. Anything else will make the task of finding your dose range more difficult.
Does that mean I can’t start with 10 mcg or I can? 
I would say you could but if yoiu want a to go for a lower concentration, fine.
Personally I’ve always got TAC in 10mcg and its been fine.
How old are you? I’m 23 with low T levels
5-10mcg to start and 6% Neroli smells amazing really! If you planning to use it in the bedroom 20mcg is a good dose.
Already paid for the 10mcg… Does that mean . 2 sprays will equal to 20 mcg?
Yes, 2 sprays of a 10mcg/spray bottle will give you 20mcg total dose.