Your doctor gave you the right information, so no need to panic. Yeah, 48-72 hours is a long time when you feel awful, but that's actually the normal timeframe for you to really start noticing a difference. Amoxicillin works pretty fast on bacteria, but your body takes time to recover - throat inflammation doesn't disappear overnight even if the antibiotics are doing their job.
What helps while you wait: take paracetamol or ibuprofen to ease the pain and fever (just because you're taking antibiotics doesn't mean you have to suffer unnecessarily), throat lozenges, rest. A lot of people think nothing's working because they expect to feel perfect in a few hours, but that's not how it works. After 3-4 days you'll clearly feel better. If really nothing changes after a week or if it gets worse, then yeah you should contact your doctor - but in your case you're probably just at the beginning of the process.