There is only one Astros game on Dish this week, of course the regular season for them doesn't start until Friday, but the Fox regional sports networks do not carry all the games anyway.
Unless you live in the southeast part of Texas, you will have trouble getting more than 25% of the Astros games, because most of the rest of the MLB area is covered by Fox Sports SouthWest and they mostly carry the Rangers.
MLB network reads your IP address and determines where you are through that, so unless you are savvy enough to be able to spoof your IP address, you are stuck.
Being in north Texas puts you square in the Rangers backyard, so that's what you get.
If the Astros were performing better on the field, maybe they would get more play on FSSW, not be relegated to FSHouston primarily.
FSSW carries about 75%, maybe more I haven't done a detailed check, of the Rangers games and the rest are on the local TV station KTXS channel 21.
Similar with the Astros, some of their games are only on local TV and there are stations aroud the state that may carry it in other locals.
We have a local sub-channel that carries the Rangers KTXS 21 games locally from time to time.