Your milk supply may not even be as diminished as you think, he could be having a little growth spurt right now and eating more because of that. Every time mine had one, it would seem like something was wrong with my milk, but I just kept putting him back on the breast and it would increase. Don't offer formula first ever, if you can start going back to that night feeding instead of giving a bottle, and drink lots of water.
When my son was about 8 or 9 mos my husband lost his job and the stress totally affected my milk supply. It was really bad and I had to supplement with formula after almost every feeding. I just kept doing the breast first. I also had good luck with an herbal supplement called More Milk Plus, by Mothers Milk (i think that is the brand), I got it at Whole Foods in the pill form. It has fenugreek as well as some other herbs in it.
The last thing I did that really seemed to help was to nurse my son on one side, then switch to the other, then go back to the first side again, then back to the second. You have let-downs multiple times so it helped him get more milk, and stimulated the production more. Only after that did I give him formula. After a couple rough weeks, it was better.
Good luck, it will probably turn out fine. But if it continues to be too stressful for you, don't feel guilty about doing what you have to do for yourself. Happy mama is what is best for baby.
PS- I just saw where someone mentioned skin to skin contact. I forgot to mention that one too. Keeping your shirt off and laying him naked on you while you watch tv, or if you have a moby wrap and can "wear" him shirtless, that will help too.