11 weeks postpartum, no period yet. tubes removed

I'm hoping somebody could reassure me that this is normal. So I delivered my 4th baby on Sept 19th. I bled for about a month straight. then it stopped for 2 weeks. & at my 6th postpartum week I had my tubes removed because we're for sure done having babies. I bled for another 5-6 days afterwards which was normal due to the surgery. & now I'm at 11 wks postpartum & still haven't started a normal menstrual cycle yet. is this normal? I've called twice to speak to the Dr about it because I was having some pain/cramps after surgery & I was told twice that the pain was normal but as far as the cycle goes they can't really say when I'll start a normal cycle or whether or not the cramping was due to anything menstrual related. So I'm just wondering if this is all normal & maybe my body is just taking longer than usual to bounce back now that I'm a little older or having so many babies or what. & I've taken 2 pregnancy tests within these last few weeks & I'm surely not prego! if I was then some Dr would be getting an earful! Lol. any advice or experience with this topic would be greatly appreciated!