Your own benefit was corrected, due to miscalculation in the prior estimates, by the Windfall Elimination Provision. (Prior to its application when you actually applied and the SSA was provided true lifetime earnings information, your estimate had included a welfare increase, which you were not eligible after your true earnings became evident. See below about WEP.) Your own benefit was also reduced by about 30% when you decided to collect it early - i.e. collecting 48 more months of benefits that had you waited til full retirement age.
Now, with regard to dependent benefits like spousal benefits, there are laws in place that say none of us can collect two government retirement amount if one is our own and one is a "dependent" benefit we didn't work for. This applies not just to government workers, but all of us. The Government Pension Offset (GPO) ensures that government employees don't get a dependent benefit like an SS spousal benefit if they are not actually a dependent, and the SS similar law prevents a non-government employee who gets the government SS benefit on her own work, from getting a second person benefit based on husband's work. See below for more on GPO.
Your OWN SS benefit it limited by the WEP (Windfall Elimination Provision). That provision ensures that your SS % rate is the same that used for people who earned the same amount as you over their lifetime - previously, your reported lifetime earnings that the SSA was a ware of failed to include all of your income (namely, that part you earned and didn't pay SS taxes on). The total amount is important because that amount determines if you were a poor lifetime earning (who should get a 'welfare' %rate applied to average lifetime monthly earnings, to get your end SS benefit amount) or a normal earner. Poor earners may be as high as a 55% figure applied to get them their benefits (so it won't be too low) while normal/high earners will get far less, as low as 25%). Because you were not a poor earner over your life after all, your estimate was based on wrong %, it gave you the welfarebonus, and so WEP recalculated it to reflect your true earnings and appropriate earned (not welfare) rate.
it is the GPO which effects your survivor or spousal SS benefit. GPO is what prevents 2 government pensions: our OWN government retirement PLUS a dependent benefit on a spouse's work record. The rule of no double dipping applies to ALL people, even those only on SS. It says that if we have our own SS benefit, but are also otherwise eligible for a spousal or survivor benefit from our spouse's SS, we can't take both, we can only take one (obviously ultimately we take the higher one). GPO causes that rule to be applied to other government pensions as well, and it does so by saying: If you have a government pension, and you are also otherwise eligible for a spousal benefit, you can't take both in full. Rather, your SS spousal amount (that you didn't earn) will be reduced by a figure equal to 2/3 of your government pension. Thus, if you have a big government pension, it is less likely that you will have any remaining SS spousal benefit. If you have a lower government pension, it is more likely you get it topped off with a piece of SS spousal. So, the 2/3 rule is GPO and ONLY applies to a spousal benefit, NOT your own SS benefit. On the other hand, the WEP will reduced your OWN benefit,but it never eliminates it altogether.
Finally, note this: A spousal benefit for people who collect SS early, at 62, is far less than even50% of their spouse's primary insurance amount. So, while you can apply for it if you haven't already, if it is less then your own, you will not want to switch to it, as you'd be losing income. Remember, all of us are always ONLY allowed one person's benefit per person - we can never take our own full amount and a full spousal amount, just one, so we take the highest.