You poor love, I empthize! I have had them quite badly this pregnancy (and am only at 27 weeks) and they can sometimes get bit worse postpartum. Not always, though - yes, its probably due to pelvic pressure generally, and enlarged blood vessels there generally, and the extra weight etc.
I also ended up with a section last time, and first poo ditto - urgh. All I can recommend is buying a large bottle of Lactulose in case fruit not enough after your section (pain meds cause constipation), and also buying some Anusol with hydrocortisone. My gp said it was fine, and the one without HC does absolutely nothing for mine - the one with HC does seem to soothe and shrink.
Mine are usually internal, and - sorry if TMI - the best tip I've ever ever had from my GP was to try and gently shove any that decided to pop out back in, whilst under the shower (ideally) because when in they get less inflamed, and obviously hurt a lot less.
HTH even a teeny bit!