Sorry, as I'm sure this is asked all the time but whenever I do a search it comes up with bizarre things!  
I am 20w4d with mono/di boys and just this week started feeling flutters/kicks.  I am feeling them every day but there is not a pattern and I also tend to only feel Baby A. (A is breech on my left side and B is head down on my right side).  I'm feeling the kicks in my lower left quadrant so I am assuming it is A.  I have felt B a few times and that's usually higher up on my right side.  
My questions are:  when should I be concerned that they are not moving every hour, two hours, etc... and also, should I be concerned that I feel A much more than B?  
Thanks in advance for any stories of how it was for your during your pregnancy! 
                Me (37) DH (39); PCOS changed to Unexplained, changed to DOR in 2012 (finally a correct diagnosis!); 
Started TTC 2009 with RE after 6 months.  
Clomid + Trigger x2; 
IUI + Femara x1,
IUI + Follistim x2;
IVF #1 (MDL) February 2013- BFN.
IVF #2 (antagonist) May 2013, First BFP of my life. 
Identical twin miracle BOYS (!!) headed our way- due date is technically 2/4/14 but c section is scheduled for 1/7! 
 

Re: Movement questions
They told me to not worry about kick counts until their movement is strong enough to not go unnoticed. For example, at 20 weeks, I still had to be holding still to feel them, whereas at 30 weeks I could be walking and it was no doubt that they were going crazy in my belly.
Our beautiful babies