Since J is under 2 years, and still under the weight limit for rear facing, he should remain rear facing if at all possible. What seat is he currently in? Also, it's a 1 inch rule, not a 2 inch rule. He can continue rear facing in the seat as long as he's within the weight limits (is your seat a 30, 33, or 35 pounds seat?), and has 1 inch of seat shell above his head. Since money is tight, I would reccomend the Cosco Scenera for $35-60 or the Safety First Uptown/Avenue for $65-90. The Uptown and Avenue have a taller shell than the Scenera and more padding/foam as well.
This is the proper way to measure how much room is above a child's head. Imagine a line at the top of the carseat (the top of the shell, don't include cover padding). Imagine another line at the top of the child's head. Both lines should be at the same angle as the carseat. If the child has more than 1 inch between the 2 lines, he still fits in the carseat RF.
This is the wrong way to measure the space above the child's head. The line should not be level with the ground. It should be at the same angle as the back of the carseat. This looks like the seat is outgrown, but she really has more growing room.
Here is a picture of a child with 1 inch above her head. She now needs a new carseat to remain RF, or needs to turn this seat forward facing.
*NOTE- These pictures were used with permission from their owners at www.car-seat.org*