Why does bitcoin price seems to pump around this time of the year?
Probably because it happened last year, and the year before it as well. And in that regard people will just assume it will happen again, which you seem to think as well. As result you will see people anticipating on a likely break-out in the price by starting with buying up some "last minute" coins, in order to be ready to sell when the price really rockets up.
That's probably why, I was reading a post in a thread about the Kraken in service discussion in which someone said he tried to deposit £9K in September to get in early because he anticipated the price going above £500. There are also other people in that thread who deposited in anticipation of a pump. This time last year the price doubled and people are buying because they anticipate another pump.
I'm trying to deposit £9K and have supplied proof of earnings for way over £25k.
I made this deposit back in September when BTC was < £500 in an attempt to get in early. I've missed that boat.