Love the board Susie. Nice job.
With regard to the end grain issue; one way to do it is to cut the pieces using a block stop on a chopsaw so you get them all as close to the same size as possible. When you glue it up, glue it face side down so that the pieces are as flat as possible and any variations are on the underside, then sand the whole thing using a random orbital sander rather than a planer. I've done one like this and it makes a really hard wearing chopping board - you can also get some great patterns with the endgrain. I finish mine with a foodsafe finish but Danish Oil is also considered suitable for chopping boards.
The planer will NOT like doing the end grain and, apart from blunting the blades in no time, you end up ripping chunks out of your board, especially at the edges. The problem is that doing an end grain board involves having the grain on the blocks going in all different directions so there is always going to be somewhere that is going against the blades of the planer. Trying to get a clean surface is very frustrating.
H.