My response applies to both male and females.
This is a female I'm taking about
Yes, you can be asymptomatic, and many males do not know they have it because symptoms are either very minor or they do not exhibit symptoms at all. In addition, if you're a female, I've read that 50% of women will not show syptom within the 5-28 day window that symptoms typically appear. Bottom line is, yes, you could have had it for 10 months + wiithout knowing it. Either you didn't exhibit symptoms or they were so mild you didn't know it was anything to worry about. The good news is that treatment is easy and effective with Metronidazole or Tinidazole.
Yes, typically you would develop symptoms within months of contracting but it is possible to go that long.