I'm female, but live in suits and have the following advice:
If the jacket fits well, and the trousers don't buy the suit
You can add false hems to short trousers, but need to check the lenght of the hem fits before you add a short hem
Always buy a second pair of trousers, they get far more wear and tear then jackets.
If you are a daily suit wearer try to have 4-5 that you can rotate, and dry clean them once a month.
Finally in terms of suits not fitting well, the OH bought a suit from Paul Costello last weekend (in his outlet in Banbridge before you all think we are loaded
) and discovered something we never knew. Most good quality mens suits have a huge seam in the crotch, from back to front, of up to 2 inches so they can be let out if you get that "have a look at my lunchbox" effect, while the trousers look great elsewhere.
So if you are buying a suit, check the back under the waistband and see if there is spare fabric there for letting it out
Helps with trying to match jackets with trousers !