Thank you for the detailed history. Since the pressure is specifically in the anal region (not vaginal) and increases with exertion/straining, this could be due to weak pelvic floor muscles after childbirn, mild rectal prolapse, or hemorrhoids/piles. Bloating and abdominal discomfort by evening can also add to this pressure feeling.
Next Steps
Please consult a Colorectal Surgeon (Proctologist) for a proper anal/rectal examination — this is the right specialist for anal-region symptoms. A Pelvic Floor Physiotherapist can also help with targeted exercises, since general Kegels may not fully address this. Continue high-fiber diet and good hydration meanwhile.
Health Tips
Avoid heavy weight training and heavy lifting (including prolonged carrying of your child) till you're evaluated, as repeated straining can worsen pelvic floor weakness. If you notice any bleeding, lump/swelling at the anal opening, or worsening pain, get it checked sooner rather than late