IS this the WH in your 2007 Starcraft Antiqua?
It's going on 7 yrs old......so a good cleaning/flushing first and a new anode rod (if needed....no need to replace until 75% of rod has deteriorated)
Check the shower hot/cold knobs being closed vs just handle shut-off as suggested.......hot/cold being left open allows cold to mix with hot causing just warm water
Then remove the set of t-stats (both are on one bracket held in place with one nut)
Check tank area where t-stats contact tank wall and make sure they are clean.
The t-stats either work or don't.....just a simple snap-disc that open at 130*F (normal) and 180*F (high cut off)
Usually you will get 'very hot' temp due to poor tank wall contact (or normal t-stat not opening) vs warm.
After a heating cycle you can check temp of water via PRV (pressure relief valve). When gas shuts down..turn water supply off, open facet hot side to relieve pressure then open PRV in outside compartment with lever (caution) and see if water is HOT.
IF it is then WH is heating....just have cold being mixed (either shower OR WH BYPASS valve is still open)
IF water coming out of PRV is just warm..replace the set of t-stats and flush tank real good.