Is it normal to still bleed after the 4th weeks of having the marina iud? And I'm nursing ?

I put the marina right after my six weeks after delivery I'm not ovulating since I'm nursing so i was nit bleeding! Now I'm bleeding spotting some days and bleeding some! This been going on for 4 weeks now:( I also feel very agrsvited sad and moody:( i read si much negative stuff about it my dr keep telling me it's the best. And just hang in there! I'm very stressed i wanna remove it!! What do u guys think of the marina? How long did u bleed after insertion? And when the bleeding stop is normal to start bleeding again after intercourse??