Kevsy123,
The fact that you get leg and buttock numbness when sitting, that tends to be the sciatic nerve. This is usually due to compression of the sciatic nerve as it passes under the piriformis muscle and out of the buttock at the gluteal fold (the lower edge of the buttocks).
A disc herniation, pressing on a nerve root, would cause a radiculopathy. This is numbness/tingling and pain in the dermatome of that particular nerve root. Such as, if it was the L5 nerve root, then the lateral side of the leg and top of the foot would be involved. The S1 root would get the lateral border of the foot and the back of the leg.
If your lower leg pain is worse than your back/buttock pain, then it is probably from a disc problem. But, if it is mostly in the back of the thigh, buttocks, back, then it is most likely from the sciatic nerve.
In terms of a disc herniation, a lot of research has been done as to the best treatment for these. It used to be taught that when comparing how patients did, between those treated surgically and those treated conservatively, at two years there was no difference. But, the patients treated surgically, felt better sooner. Since surgery has become much safer than in the past, most patients do not want to put up with the problem for that long and will elect surgical intervention. Again, this is for disc herniation specifically, not for nerve roots compressed by other materials such as the annulus, bone, or hypertrophied ligaments.
Most spine surgeons will allow their patients to do any activity that they are able to do. They definitely encourage the patients to stay as physically fit as possible, as a fit patient has less back pain than the sedentary patients. maintenance of proper weight and cardiovascular fitness is important. Strong core muscles are also very important.
If you feel that you need to see a spine surgeon, do so. A thorough evaluation and possible MRI should be done.
Good luck.