It's a big decision and I think only you guys will know the right answer. There are obviously things to weigh up on each side.

If you would prefer to wait but it is the pain that you DH is in are there any options with storing sperm etc? So he can have them removed?? Or with your part time job how long do you have to work there to get the maternity leave? If you worked up close to your due date (which would be a bit easier because of pt) how long would you have to wait to start ttc so you would be eligible? If it's still ages perhaps you could approach your employer and ask them if you were to have another baby before the time is up for maternity leave would they keep your job for you??