Trying to conceive again at 35

I am currently in the follicular phase, I recently started bbt charting for the first time and using opk's. I am 35 and have had 3 children. The funny thing is the second and third child were unplanned, but now that I am trying I have had no luck, for a few years now. I decided it may be best to give the charting a try as I tend to have irregular cycles. I am hoping this will give me some insight into my cycles. I am really hoping to get pregnant with the 4th child as I am going to be turning 36 soon. I had really thought I would be pregnant before now. With my first pregnancy that was planned it took a year to conceive my son. After that we tried again, but had no luck and we eventually gave up and conceived again only to mc. I have had 5 pregnancies, two ended in miscarriage. I have not gone beyond chrating and such yet, but if nothing happens in the next few months I will probably go ahead and have the hpg my doc wanted to do. I love my kids and feel so blessed to have been able to have them.