It's completely normal for your period to be off whack after you have a baby. Are you breastfeeding? If so, it may be affecting your period. Some women don't have periods until they stop breastfeeding. This is kind of rare, but normal.
It is really important to be on birth control after birth if you don't want another baby so fast! You are extremely fertile after birth and can get pregnant like a finger snap.
Since you said you don't have health insurance, you can go to planned parenthood. They are not just for abortions. You can go there for check ups and if you think something is wrong too. I go there for my yearly GYN visit and get my birth control there too. They do everything on a sliding scale and an exam costs $60. Birth control is like $20-$30 a month and they have lots of different options if you don't want to take a pill every day.
I know, personally, that $60 can be A LOT of money to drop on an exam you don't even want, but it is the cheapest option for women, like us, who don't have health insurance.
And you really really need to be on birth control if you don't want another baby so soon! At least use condoms or something!
But if you do want another a baby all the more power to you! I think moms who have two in diapers are so brave! It is hard work and I have a lot of respect for any women who has the strength to raise two babies at once.