Don't worry yourself sick or stress out over the thought of getting your boy neutered! You still have several months to go
I wouldn't be overly concerned about the safety of a neuter (of course there is always a risk when you put your pets under)...it's very routine and generally non-invasive with a quick recovery time. We got Teddy when he was 9 months old and scheduled his neuter after his first vet appointment for the following week. He also had a couple of retained teeth removed while he was under as well.
And hopefully someone here can post an updated link to a puppy growth chart. Toki weighed 3.1 pounds at 10 weeks and is a little less than 8.5 pounds at 1 year 9 months.
We would love to see pictures of your little Kipper!