We do really short PTO meetings and have them during a "family night" event (science make & take night, winter break program, reading night, math night, etc.). Perhaps that's something to try as well?
It sounds like your executives have already split things up pretty well to try to alleviate putting too much on any one person...
At the same time it almost sounds like you have gotten totally away from utilizing committees, which is the place where non-regulars can try to get involved. If the same couple of people are doing all of the major stuff behind the scenes and then just reporting to the rest at the monthly meeting, the non-executives are going to start feeling unwanted...
So I would still look to try to form committees for some of your events and promgrams. If no one signs up then you can keep it as is, but at least try to bring these others into the major events and programs...
Next it sounds like you really need a membership drive. This should really be a job for your President, but with only 10 regulars, you need to ast. One thing that we have done is get highschool volunteers to provide childcare, which has allowed husbands to get involved. We now have 6 men activally involved, where just three years ago there were none...
It does sound like you are a bit overloaded. First of all, your FAMILY is your first priority, so don't feel bad if you have to let some of your PTO activities go. Next, here are some suggestions that might help in a couple areas:
Empty board positions: If you have just been putting out a general call(announcements at meetings, newsletters) and no one is responding, try approaching some parents face to face. Sometimes people here an announcement or see a blurb in the newsletter and they think "Oh, someone will jump on that." Unfortunately if everyone has that view then NO ONE steps up. Besides it's harder to say "no" in a face to face.
Your board might also look at the open positions and see if there is a way to share them or divide them into smaller jobs. It can be much easier to find 3 people willing to each take on one or two projects than to find 1 willing to take on 6 projects. If you have already divided the duties among the existing board, then you already have a good idea of what events/programs are and aren't dependent on each other.
Board members taking on committee duties: Get those committees reinstated! It's fine to have a board member sit on each committee, but let someone else be in charge. Your board members have enough of their own duties to accomplish without adding committee chairperson to the list.
Meetings lasting 2 hours: Have an agenda for each meeting that will cover all needed topics within a 1 hour timeframe and then stick to it. Communicate at the beginning of the meeting the goal of completing the meeting in 1 hour and that in order to accomplish this there will be time limits on discussion of items. Have one of the other board members be a timekeeper during the meeting and give "warnings" as the time limits are approaching.
Your board may also want to take a look at all of the decisions that are being made during the meetings. The elementary group I used to belong to initially had meetings that went on forever because they let discussions just go on and on and because the board had no power to make any decisions. A group of us worked to get that changed: We got the meetings down to 1 hour or less and really streamlined the operation of the group by having a very clear budget that was approved at the beginning of the year which allowed committees and the board to move on projects without voting on every little thing at general meetings. The board was also given more power in the areas of fundraising decisions, program and events plans, and we were allowed to do a board only vote on items of $100 or less.
Lastly, take a good hard look at the events and programs you have planned for the year and your volunteer needs for those events and programs. If you don't think you can get the volunteers needed, then seriously consider cancelling the event. It can be a tough decision to make, but your entire board is going to quickly burn out if you don't take some drastic measures. Be sure to clearly communicate this to all of your parents as you proceed on this decision making process. Sometimes if a program or event is important enough in the minds of some people, they will jump in to help make sure it happens.
