11 weeks is about normal for it to stop.
With DD mine stopped at 10 weeks, and with DS it stopped at 15 weeks.
With both of them it stopped relatively suddenly - over a few days I just immediately started to feel better and get my energy back.
That's a really good sign that your placenta is taking over the production of hormones to support your pregnancy just as it should be - this happens in the 10/11th week.
It was crazy...particularly with DS after being sick for sooooo long it was like a new lease on life!

Congratulations and enjoy! Second trimester was absolutely wonderful for me - so much energy, no morning sickness and no big bump in the way yet!