Missed Period & breastfeeding question...

My little one is just now one year old as of 2 days ago. It goes too fast! I've been solely breastfeeding, and she still nurses a few times throughout the night & 6-8x during the day. I don't pump.. She's probably now at 65 % breastfeeding and 45%table foods but just in the last 2 weeks. Prior it was 98% breastfeeding. In June I had my first cycle and we have been TTC for another one, but I ended up having a my first pp cycle. With my other children I had my first cycle in the 1st 8 weeks of pp so this was a nice surprise to go 10 months! So obviously I wasn't pregnant. July comes in & on the 28-day Mark I have another cycle but we have not been able to do anything since before my June cycle because he pcs'd and moved so we haven't seen each other and won't till holidays. So it's impossible I'm pregnant because I've had 2 cycles since our last intimacy encounter. Now I am 6 days late and I'm wondering if because I'm still breastfeeding that I can skip cycles or my hormones haven't balanced yet or something. This is new to me given with my other kids I soley breastfed, one even nursed every 2 hrs around the clock till 13 months old, and still I had a regular 28 day super predictable cycle 8 weeks after birth. A little more info is I had been using lh tests so we knew if I was even ovulating or not. In June, right before my cycle, I definitely had positive tests so it was a disappointment that I didn't get pregnant. I haven't had a positive one since, though I did stop testing for 10 days because we didn't realize how easy it'd be for my husband to visit on occasion and I may have missed a positive in those days. I have my one fear though. It makes my heart sink. I'll be 43 next month... Is it a sign I could be starting menopause? I don't don't why, but I'm just not ready for that at all yet and had really hoped I'd have a couple of more years to have 1 or 2 more children. Would I have other signs or symptoms and would I still be producing milk if I was premenopausal? A lot of questions and I have no idea where else or who else to ask. Hoping some of you have experience or have heard medical things to know. Thank you all!