going under by 3 for one day wont do any harm and you dont need to have 33 today, but doing it on a regular basis will slow down your losses. What you could do ,is add up all you spare points for a treat at the weekend. i always save some points for some wine on a saturday night.
Some people choose to count their point weekly rather than daily so for you 30 x 7 would be 210 points per week and as long as they all go over the week you shoud be ok , even if yoi have 16 one day and 40 the next it will balance out.
No one is advised to have less than 16 points in a day
hope this has helped