non-salaried income-meeting financial requirement

Hello all,

i am applying for a spouse visa application for my husband in Pakistan, i have collected all the relevant information but am having some difficulty wondering if anyone can help.
I am a permanent employee at a company for 2 years, however i am on non-salaried income-hourly rate pay. My past 6 months payslips all total to £9903- which is £19806 when calculating annual salary, so i am meeting the financial requirements of the visa, BUT 2014 summer i was out of the country for 3 months for marriage to husband, because of which my P60 for 2014-2015 is now showing annual salary of £15000. ...
i am getting worried that my p60 shows a low income - but my payslips are fullfilling the requirement and adding up to above the 18600 threshold.
would it be a good idea if i got an accountant/solicitor letter to explain why P60 and payslips don't match?
i have a letter of employment confirming my job and pay etc but but sure if it will be enough and may affect my case.

thanks