Sounds like your diet is off. What worked in the past may have changed. Look at your carbs around training time. If you are dieting and don't want to add carbs, try moving your carbs around, stacking them up around your training time. Maybe change your carb source. Sweet potato is a great source of carbs in your pre-workout meal. Fats can play a roll in fullness too. So something like beef preworkout works well. combine these 2 foods, and you have a great source of pumps.
As for supps, creatine, citrulline malate, and other NO products can make a difference. Intra workout carbs like HBCD are good too, if your diet allows more carbs. But get the real food carbs and fats timed out first and see how that works, then build off it that.
If you are using gear and pumps seem to be reduced, you might be taking too much AI, staying too dry. Or if your T3 dose is too high, this will flatten you out.
GH or GH and IGF are great for pumps. Take it a step further, insulin works very well. Some of the best pumps I've gotten are from insulin, but not in the contest season. If you're interested in slin, you'll want to spend some time reading and learning.