You dont have to have it..but it helps as it is part of the environment that helps the sperm swim up the cervix etc and catch the egg- it latches on to the stringiness of the ewcm to swim up.
it is possible to have what is called 'hostile cm' which means it doesnt let the sperm through the cerivix, or worst case, kills the sperm.
However, this is rather rare and in your case i would look at ways to increase it if this is your worry.
As far as pinpointing ov- there are no better ways than using opk's-but better yet, temping. I dont do temping but its a foolproof way. I use a cbfm and it tells me when i am about to ovulute and when i have. Your cm can be a great help in telling you when you are fertile-however its not an indicator of ov as it can happen at any time during ov- you can have residual estrogen in your system which will produce ewcm even after ov. I.e. i had ewcm for a week before i ov'd this month as o ov'd late.
Basically, there's no easy way in this ttc malarkey except fighting it out and hoping for the best!!
