Girl, I'm just as confused as you are. I have the opposite problem with mine. Got it in March 2017, not to prevent pregnancy since I already had a tubal ligation, but to stop my periods. My doctor said it might or might not do that, but I went ahead and did the insertion and it worked really well for that purpose.

I had some spotting on it, especially in the first year, maybe 4 or 5 light and irregular periods. In year 3, my flow has been basically nada. I'm starting to feel a little concerned because this thing is supposedly expiring in 2 months and my periods haven't come back. I don't know if it is really just that effective for 4-5 years off-label, if I won't get my cycle back until it's removed, or if I went through premature menopause or something.

What I have read is that it always works for a minimum of 3 years, it's just that some people bleed with it and others don't. I don't know why that is, but you're safe if you got it in April 2018. According to my research, different people just respond to it in different ways.