u/Proper-Ad-4852

Hi everyone,
I’m trying to figure out if my AC is performing normally or if there may be an issue.
System Info:
Goodman condenser manufactured September 2015
Model VSX140301AA (appears to be a 2.5-ton, 14 SEER unit)
R-410A refrigerant
1,300 sq ft one-story multifamily unit in Oklahoma
Recently added attic insulation
What I’m seeing:
Thermostat is usually set to 72°F
In the morning, when it’s around 80°F outside, the house is 72°F
When it’s around 93+°F outside, the house is usually around 75°F
On 95-100°F days, the house gets up to about 76°F and can’t seem to maintain 72°F
Electric bills are around $300/month during the summer (SUPER EXPENSIVE)
The system does cool the house overnight and eventually gets back down to the set temperature. It just struggles during the hottest part of the day.
I’m wondering:
Does a 2.5-ton unit sound appropriately sized for a 1,300 sq ft one-story unit in Oklahoma?
Is a 3-4°F temperature rise above setpoint on 95-100°F days fairly normal?
Does the $300 electric bill suggest the unit is losing efficiency?
What should I check first before considering replacement? (refrigerant charge, dirty coils, duct leakage, airflow issues, etc.). I had a Technician come out last year and they said return air is fine.
Any thoughts from HVAC pros or homeowners with similar-sized homes would be appreciated. Thanks!