Ovulation test

My <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> said they the 28th and 29th were my most fertile days but i started taking my ovulation test on Monday and it was negative then positive on Tuesday and back to negative since Wednesday and this morning it's a very faint Line. Has anyone else had this?? So did I ovulate just in between mon and Wednesday or should I continue taking the test? I'm so confused