Is it normal to need to think about blowjobs to come?

I am a 22 year old married woman. I can only come when thinking about giving blowjobs or watching blowjob porn. I try to think about having sex or getting eaten or try to think of nothing and just feel but cannot get turned on enough to come unless I go back to thinking about blowjobs again. Is it normal to need to always think about something specific like that to finish?