Feeling huge after having my baby!

Before I had my baby I was between a UK size 12 and 14. Since having him (he's now 4 months old" I have felt massive and huge and disgusting. I am now between 16-18 UK size. I literally hate this so much i feel like shit and I feel like I'm too vile to go and do anything. I want to go to the gym but I really can't afford it and I know that the gym works for me like it did before. I can't do exercises at home as I'm unmotivated at home and have baby there aswell so get massively distracted. Anyone else feeling this way?