Ok, now everything works as spected, just for a mistake.
When I did changes on the /etc/pf.conf, I relaunched the PF

just with:
# pfctl -d

# pfctl -e
I thought that was enougth to make the changes affect pf, but NOT,

I needed to use this instead with my actual config:
# pfctl -d

# pfctl -ef /etc/pf.conf
And everything goes as spected. I seted up a little dhcpd and

all my network works as I want, from now I will make changes

to pf.conf to make it more stronger than now.
There is another way to make nat on OpenBSD, without using PF ??
Thanks for all

 -Jesus