Fertile CM advice TMI warning

Okay so I don't seem to ovulate regularly, and my CM is only rarely (I mean like one in 6 months) egg white consistency. Typically I have watery/creamy CM. Only a few times in the 2 years we've been ttc have I gotten this kind of CM.

My question is, for those of you that DO get it, does it last all day? Mine is only like that for a few hours when it does happen. Do I want to be actively having sex as soon as I see it? Or just within 24 hours?

For those that NEVER get egg white CM, what type is most common for you during 'fertile time's? How do you determine when to have sex?

I know we're all different so I just wanted to ask a wider range of women. Looking at ovulation tests again as the only time I conceived I was using them. In a few more months I will be arranging a fertility check up to find out if there is a reason I haven't been able to conceive outside of my one pregnancy that ended in a loss. The only reason I have not gone sooner is my midwife said to wait it out.