ah, split boxers, nothing better. 7lbs in 2 weeks is OK for now, but that will probably taper off, and it should taper off, it isn't possible to keep gaining at that rate without it being vastly fat, but don't stress for these first few weeks.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano