Possible signs of infertility?

My husband and I have only been trying to a few months, so I'm not leaping to any conclusions yet. But I have some questions if any of you would like to speak into it. I have a very regular cycle, but my bbt rarely ever changes- and my temp definitely DOES NOT go up while on my period or ovulating (and yes, I take my temp first thing before getting out of bed in the morning). Could this be a sign of low estrogen? Also my boobs are ever rarely sore, even around my period. And my periods are always super light- but rather long, as in 7-8 days. I'm 26. Thoughts?