I'm trying to get pregnant

im trying to get pregnant and I have a doctors appointment next week but I have questions now, my question is why do I only get that egg white cm when I'm "Horny" I never get it randomly like I'm ovulating but after I get off my period I'm always extremely horny and it's easy for me to get wet and when I do it's always a lot but it's never just there randomly I think I might be infertle because I was on birth control so long , depo for almost 2 years then I had the IUD for a year 1/2 I've tried on the high risk days and I just can't get pregnant I'm giving up hope