Houston is not so wack that you would have more than one congressional district on your ballot. You only have one representative in the House. Not sure which particular district you live in, but if you're in one of the two you listed in your photo, you'll have either 2 or 3 candidates to choose from for US Representative:
US Representative, District 7:
James Cargas - D
John Culberson (i) -R
US Representative, District 10:
Tawana W Cadien - D
Bill Kelsey - L
Michael T McCaul (i) - R
The lack of a US Senate race for you this year is a function of 6 year Senate terms and only two Senate seats to be decided over the course of three election cycles.
Hmm. Always thought they were 4 years.