Yes i have done since about your stage actually! Its absolutely horrific at times and the bigger baby gets it can be quite hard! I find if it eat a big meal it tends to fill my tummy up and I am even more breathless cause my lungs are squashed. My main suggestions that I've learned is: small frequent meals, breath deeply and be aware of breathing when climbing stairs or exerting yourself and be sure to take frequent deep sighs as you normally would, but almost induce them because it gives you a good burst of oxygen.
Hope that helps if at all, cause everyone is diff I know! Xx