Most probably you under rotated or as said you got into strong headwinds.
Possibly also if you are relatively lower weight and high thrust(no ASS).
If the FD go back in a short period of time from 20 to 15 its probably due to an under rotation/speed too high,after corrected it goes back to a normal 15 deg(standard ASS and weight ratio).
Most airlines restrict the pitch by pilot action to 20 degrees,ie disregard FD).
Remember 25 degrees pitch up is considered an upset and needs to be dealt with as laid down in your QRH.
Your captains dont teach you anything?worried to ask them?