Can you take a picture of what you mean? I'm having troubling figuring out if you mean you're cutting off the point or what's happening exactly and when in the block assembly it's happening... When you join two hsts, you won't see the points yet because there is going to be extra on all sides for the seam allowance, and will look like this (seam allowance in green):
[ATTACH=CONFIG]524517[/ATTACH]
If it looks like this:
[ATTACH=CONFIG]524518[/ATTACH]
when you join the center square to the hst unit, you'll get this:
[ATTACH=CONFIG]524519[/ATTACH]
When I make hst stars or points, I make them too big and then use a 6.5 x 6.5 square ruler with a diagonal line to trim them down to correct size. Another extremely helpful tip is to make sure to 'nest' your seams. Press one hst toward the pink side and one toward the white side. After trimming put the hsts wrong sides together and you can nest the seams perfectly into each other.
Now, about pressing...
http://www.mccallsquilting.com/mccal...icles/pressing