R.H.
I second the warning about 'binding' your breasts, even with a sports bra. The only times I ever had issues with clogged ducts was when I tried to wear a sports bra or a 'regular bra.' I had the best luck with wearing tanks with built-in shelf bras.
The hands-down best online source for breastfeeding/pumping/mastitis info is kellymom.com. I'd trust anything on that thorough, well-researched site over anything my doctors or my kids' peds said!
As for the mastitis issue...antibiotics are great and definitely have their place, however, with so much recurring infection there might be 2 things I would address first: 1) the pumping 'technique' and 2) the lifestyle (i.e. diet, sleep, stress, water intake)
I exclusively pumped for my son for a long time, so am familiar with different postures, ways to hold the pumps/hands-free, etc. Have you tried changing anything about the way you pump? I noticed sometimes I would be tilting the horns, pressing them into my breasts, or leaning on them a bit, or something like that, & once corrected, it felt better.
I'm not sure if I would have been able to pump exclusively for more than 2 days had it not been for the information I found on Kellymom.com! It also has some good tips and gives the background story behind some simple lifestyle stuff like ensuring you get as much sleep as you can (I know...I know...;), reducing your stress (I know...I know...;), drinking about twice the amount of water you think you should be drinking, **avoiding sugar/simple carbohydrates**, and getting plenty of calories from nutrient-dense foods (i.e. avocado, lean meats, etc.). Some other tips that helped me: watching those fish oil tabs (coincidence or not, they always seemed to correlate with a clogged duct or two! ??), and supplementing with sodium ascorbate (a buffered, crystalline form of vitamin C suitable for therapeutic dosing; note: this is different from the non-desirable calcium ascorbate). I get my sodium ascorbate from Central Market, Whole Foods, or online. In addition to helping prevent/treat infection in me, it's awesome stuff to take/give my kiddos too when they're up late, exposed to something, or at the first sign of a sniffle. Motheringdotcommunity message boards offer much good info as far as sodium ascorbate is concerned too. In addition to the sodium ascorbate, I highly recommend hot showers and massaging "out" the breast. It hurts like &*@%, but sooo worth it if you can dislodge any clogs.
I'd also like to commiserate with the desire to spend time with your sons v. being attached to a pump! BTDT! However, mine is also a BTDT-experience that revealed to me that the world of formula is not all it was cracked up to be in terms of freeing up time for baby bonding. My son was a miserable baby on formula and has long-term issues as a result of his exposure to formula. The >2 months it took to finally get a formula he could tolerate were insane!! Looking back, it would have been flat out *easy* to eat chicken & brown rice and just pump his milk - even if I had an infection, I'd rather me be sick than him -- I could take better drugs! - compared to dealing with all the issues that resulted from formula intake and that will affect him for the rest of his life. Your boys might not have any issues with reflux or with allergies like mine did/does, but then again, there's no way to know until it happens - and you can't go back in time. It's one of those mommy decisions that I just had to make, do my best, and go on. Regret is a wasted emotion, IMHO, but I felt it would be cruel of me to not give you a heads up on my experience -if nothing else, so that you could be more fully informed of the risks of choosing either path! <3 Best wishes to you & your twin men!