It's possible you misunderstand exactly what you are entitled to. Now that you are a widow (and I am sorry for your loss, it's never easy) you are entitled to 100% of what your husband's SS amount was. I'm guessing that's more than what you were collecting on your own.
As others have suggested, make an appointment with your local Social Security office.
And Medicare deductions are likewise straightforward. I'm forgetting what it currently is, but it's not a variable amount.
Speaking about my own personal experience with Social Security, I'm a divorced spouse. When I turned 66, my full retirement age, in 2014, I was able to collect 50% of what would be his SS when he turned 66, his full retirement age. He's four years younger, so the numbers actually work out quite nicely. Anyway, I collected that amount for the next four years, until I turned 70. A few months before my birthday I got a letter from Social Security telling me that I need to start collecting on my own, as it would be more money than the spousal amount. Which I already knew. Here's the crucial part. I needed to go in person to the local Social Security office to make the change. I'd been able to do the original claim, the one against his account, over the phone. Not the new one. I had to go in person. Which I did. It was straightforward, the change was made, and I started collecting about $500/month more on my own account.
If my ex dies, I will become one of his widows. He's currently married to someone else, so she'd be a widow also. Depending on exactly how long he lives, and I certainly hope he makes it to age 70, I would then collect at least another $500/month, raising my SS payment quite nicely. Alas for me, his family is quite long lived, typically well into their 90s. Since I'm four years older than he is, my chance of outliving him isn't all that great.
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