No period for 10 weeks?

I am a 30 year old woman with a 3 year old. I always had my period every 4-5 weeks. Never had any fertility problems, I got pregnant right away 4 years ago. Now I haven't had a period in over 10 weeks. I haven't started or stopped any birth control methods, so it's not that. I am not pregnant, I have taken countless pregnancy tests. I haven't stopped or started any new exercise routine or diet. Is this something to worry about? It seems like a symptom of PCOS, but this has never happened before and I didn't have a hard time conceiving. Could it just come out of nowhere? I gained 5-10 lbs. Could that have such a big effect? Should I see my doctor? The only change I made is I stopped taking my anti-anxiety meds. I slowly tapered off of them because I felt I didn't need them. Would that have an effect on my period? I'm starting to get concerned. Any advice would be appreciated.