I remember accepting Christ when I was 6 years old (my parents will say I was younger than that even, but agree to disagree). I never had any reason to doubt my faith. At a revival event around the age of 10, I felt a very distinct call to the mission field, and knew beyond any shadow of a doubt that I would be serving God in Taiwan. At age 14 I got caught up a sinful lifestyle that plagues many men from their teens on, and my faith suffered for it. God got ahold of me again at age 17, and my call undeniably shifted. I began working at the local Homeless Shelter and again, I knew beyond any shadow of a doubt that I would be doing urban missions for the rest of my life. About 7 years later, I once again felt my calling shift, and began pursuing Church ministry as a pastor. I have now been doing pastoral ministry for as long as I was doing homeless outreach, and feel amazingly fulfilled, as one will when they’re pursuing their God-given calling.
My point in going over all this is that at 30 years old, I have felt three distinct calls. Does the fact that I am now pursuing a call as a pastor mean that the previous calls were invalid? I don’t believe so. As you are serving Christ in whatever capacity He has called you to, remember that we are called to be servants first and foremost. Don’t be afraid of change if it means serving God the way He needs you to.