I don't think it will sabatoge your supply..if you're only offering the bottle at night then your breasts will adjust and make the right amount for your baby during the day. Be prepared for your breasts to be full during the night when you're giving him a bottle instead of you..it can be uncomfortable!

But..after a few days your body will adjust!
I started giving ds a bottle once in awhile -I gave him formula first so I could pump for that feed so I could get my "freezer" full of expressed breast milk. Then i was able to just give him ebm when i offered the bottle. I'm still breastfeeding but if dh and I go out somewhere and ds stays with my parents he has a bottle...and I would pump when I got home so my supply would stay up...but sometimes I wouldn't pump and found if that I did that too many times my milk supply would lessen but once in awhile I would miss a pump and my supply was still ok.
I hope I could help with how my situation was!
Good Luck!
S
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IUI's-4 to conceive Troy July 25/05

m/c *angel* 10 weeks July/04
IUI's-2 for bfp Sept 27/07