My Glow chart hasn't updated my calendar with my actual ovulation date.... so now not sure when AF is due and when I can start to test for PG!??

Gillian
I am 25, and only in month one TTC, so this post is coming from a place of confusion rather than stress of TTC for so long (best wishes to all who are trying 😘)
I had my mirena taken out in March and gave myself a couple of months to get my hormones back to normal. It seemed to work, I had 2 periods of 27/28 days and so myself and my SO decided to start trying.
My Glow chart initially had my getting my period in a couple of days.... however as I OPK'd and brought back negatives, it pushed my period back a few days.
As you can see, Glow has my ovulation recorded as 18th..:: but I didn't actually get my first "static smiley" (with CB advanced test) until Friday 23rd, which was my 28th Cycle Day!!! 
So I am confused about a couple of things:
1) Why is Glow keeping an ovulation recording for me on 18th? And thus affecting when my period is probably due?
2) Is it expected that my cycles could be irregular after the Mirena and this one could last up to 40 days for example?
And 3) When should sensibly take a HPT? I have the Clearblue Early Prediction tests (x2) but they are expensive so don't want to waste them!!
Would really appreciate some advice, as I feel slightly lost when I am so keen for an understanding of what's going on in my body!
Oh - and I have had sore nipples and been v emotional today.... am I imagining pregnancy symptoms??