If you're trying to cut, please be aware that a cutting diet is NOT a hypertrophy diet, so you need to adjust your expectations based on the type of diet you're following. As mentioned above, if you want to see gains, you'll need to eat for them. Its fine if you want to cut, but then set your expectations accordingly and lift to promote maintenance and not overtraining (for the fuel you're providing). Then consider scheduling a bulker phase (it can be an all out bulker or a lean bulker based on whatever your goals are - you don't have to get sloppy fat to make gains, but if you opt to do a lean bulker, expect the slower, but more consistent and more maintainable (IMO) gains. Its a slower process, but its more controlled in terms of fat gains and working w/ the fuel provided.
In terms of dimensions of changes to your current routine - read up on periodization. It might be worthwhile to pick up some dumbbells. I'd also suggest looking into some bands (check eltfitness.com) - you could use these to add resistance to a single set of DBs (e.g. if you bought 1 set of 30 lb weights or whatever) as well as adding them to your barbell lifts.