Ovulation tests advice

Using clearblue digital been testing 7days now with no sign of LH Surge being predicted. My cycle varies so i think i may be testing at wrong times plus im trying to go by Glows predicted fertile days, been TTC for 2years and just been refered to fertility clinic (awaiting appointment) for tests ect husband just had semen test done (awaiting results) losing hope everyday :-( just need advice on best way to track ovulation please. I work 15hr days so charting ect wont work for me at min.