After a month of hard work I have to pay quite a lot of things. I just got one about 200$ to invest in bitcoin. Should or should not. Please help me !

$ 200 / month is about enough income for investing in bitcoin or ETH right now. You should be glad and seize this opportunity. When the market is recovering after 3 consecutive months of decline in value. The sound and signs of recent flourishing. It seems the market is starting to regain balance and ready for a rapid growth. A hint to get started and do not waste time.
Yes investing 200$ every month also is a good amount as you can easily buy new tokens at very cheap rates during its ICO stage so you can easily buy at in cents price per coin and thus 200$ is a good amount to be invested in . Also some amount of btc or Eth as well can be purchased.