I think you are making the right decision for you. I have watched a lot of people struggle after having children they did not plan for. If you know you are not and likely will never be interested in having children, getting a vasectomy is right for you.
That being said, if things change down the road, you can always foster, adopt, or attempt to have the vasectomy reversed – the last option is not guaranteed though.
No. I pay taxes while using none of those programs and those programs are there to give people a hand up who are struggling. You deserve a roof over your head, a warm & safe place to sleep, clean water to drink and bathe, and decent food to eat. You are human and trying to meet your basic needs. People who have more can support those who have less. Simple.