Trying for a baby whilst suffering with anxiety..

I have 4 children & I am 41. I would love more children and have been trying to conceive for 6 months. I am a little worried that I might not be able to have any more children due to my age, but I still have regular menstrual cycles. Can anyone suggest any great fertility treatments please, also how would I know for certain if I am still fertile.

Thank you in advance for any feedback on this topic xxx 😗