Ma'am , its a very good thing that you are putting in efforts for brushing twice daily and i really appreciate your efforts . Plaque is a layer of soft deposits on our teeth and it is a natural thing to happen as we eat food , but this layer over time mineralises if we don't clean it and then this hardened layer is called as tartar which is not good for the health of gums and bone (can lead to teeth loosening if tartar is left for longer duration). My advise would be that you plz consult with a dentist for proper flossing technique because if not done properly then it can hurt the gums.
Next Steps
visit a dentist and consult how frequently you should use floss along with brushing twice daily.
Health Tips
Avoid having:- 1- junk food,2- too much sugary and soft food ,3- cola's, 4- frequency of eating also should be less as these things increase the frequency of plaque deposits.