Luethal phase understanding and reassurance needed please.

Hi Everyone, I am trying for a baby atm. This month was our first month trying and I am completely overwhelmed. I am adopted, so I feel I have an added worry, as mum and dad could not naturally concieve, as dad had a low sperm count. I have become a little paranoid and just want everything to be normal. I am 34, healthy and fit.

Before this month, I had no idea what a luethal phase was. This month I took my ovulation tests daily. On day 16, 17 and 18 I got a flashing smiley for high fertility. I got a solid smiley for high fertility on day 19 at 7am. Q1. Is my day of ovulation day 19 or the day after day 20? My period came on day 31. Q2. Does that make my luethal phase 11 days or does the day it arrives count as 12th day. Basically wondering how long is my LP? 

Based off of my own calculations, I think ovulation is day 20 (day after positive ovulation test). It says online any day up to day 21 is normal, wish I had been more in the middle.I think my luethal phase is 11 days, most places say anythihg from 10 and above is normal. Again I wish I was more in the middle. 

I keep getting mixed information about the luethal phase. Most sources say that 10 or 11 days if fine. Others that it is classed as a short luethal phase. How information can differ on medical sites it beyond me! 

Could anyone with any experience help me to understand this better? It is a minefield and I feel very lost in it. Have people with a 10/11 day LP got successfully pregnant? Did it take much longer?

I look forward to hearing from ye.

Thanks.