LSIL is an indication that cervical dysplasia may exist - but dysplasia is not diagnosed until a colposcopy and biopsy have been performed. Sometimes and infection or inflammation can cause an abnormal pap result - so it is possible that the abortion may have caused your LSIL. However, if you have a colposcopy and are diagnosed with dysplasia (CIN1 usually coincides with LSIL and is a mild dysplasia) then yes this is caused by HPV. It is also important to know that pregnancy creates an environment for HPV to become active (from a dormant state) and for dysplasia to develop, often this will regress once you are no longer pregnant.
LSIL is almost always caused by HPV. I don't know if your abortion would have an effect on the PAP result.
STD tests do not test for HPV. It is likely that either you or your boyfriend had HPV before entering the relationship.