White smoke from exhaust

1992 Honda Ascot Innova, 163000 Kms. For some time now, I have been noticing white smoke coming out of the exhaust when the car accelerates from rest and sometimes when reversing. I don't think this smoke is dew evaporating as the smoke also occurs when the engine has warmed up. Sometimes there is a lot of white smoke as I can see it in the rear mirror. However, don't see the smoke (in the rear mirror) when car is at normal speed (50 Km/hr). Could the coolant be leaking into the cylinder, hence, problem with the cylinder head gasket? Have not yet checked the engine oil for mix-up of oil and coolant. We recently replaced many pipes due to coolant leaking from them.
Also, the engine sounds as if it is under a lot of pressure when the car is going up hill and has not picked up enough speed.
Would really appreciate suggestions as to what could be wrong. Thank you.

But, I thought that white smoke was caused by the burning of water/coolant. Or am I wrong here.